Task - Collections - Map Basics - Book Map #51

akash-coded · 2022-03-08T05:21:37Z

akash-coded
Mar 8, 2022
Maintainer

A Map for Bibliophiles

Define a class called Book.
The skeleton of the Book class is given below:

class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    // parameterised constructor

    // override toString()

   // override hashCode()

   // override equals()
}

Write the implementation for hashCode() and equals() manually. (Important fields: id)

In the driver class, create four instances of Book class as follows:

Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

Create a HashMap<Integer, Book> called books and insert all the book objects as values using their id as the key.

After insertion of all books, display all the values stored in books.

Double the quantity of all the books.

Write a merge() function to check if a book with the id 233 exists or not. If it does, add " USA" to its publisher name

Sarfinaa · 2022-03-08T05:53:31Z

Sarfinaa
Mar 8, 2022

package week_5;

import java.util.*;

class Books {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    public Books(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    @Override
    public String toString() {
        return "Books [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

    @Override
    public int hashCode() {
        int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Books other = (Books) obj;
        if (id != other.id)
            return false;
        return true;
    }

}

public class Maps {
    public static void main(String[] args) {
        Books b1 = new Books(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Books b2 = new Books(233, "Operating System", "Galvin", "Wiley", 6);
        Books b3 = new Books(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Books b4 = new Books(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
        Map<Integer, Books> map = new HashMap<>();
        map.put(b1.id, b1);
        map.put(b2.id, b2);
        map.put(b3.id, b3);
        map.put(b4.id, b4);
        map.forEach((k, v) -> {
            System.out.println(v);
        });
        System.out.println("After doubling the quantity!!!");
        map.forEach((k, v) -> {
            v.quantity *= 2;
            map.put(k, v);
            System.out.println(v);
        });

        // if (map.containsKey(233)) {
        // map.get(233).publisher += " USA";
        // map.replace(233, map.get(233));
        // }
        System.out.println("After merging!!");
        map.merge(233, map.get(233), (oldBook, newBook) -> {
            newBook.publisher += " USA";
            return newBook;
        });
        System.out.println(map.get(233));
    }
}

0 replies

lalit-ky · 2022-03-08T06:01:20Z

lalit-ky
Mar 8, 2022

package collections;

import java.util.HashMap;

class Book {
    protected int id;
    protected String name;
    protected String author;
    protected String publisher;
    protected int quantity;

    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (id != other.id)
            return false;
        return true;
    }

    public int getQuantity() {
        return quantity;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }

}

public class BookDriver {
    public static void main(String[] args) {

        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

        HashMap<Integer, Book> books = new HashMap<>();
        books.put(b1.id, b1);
        books.put(b2.id, b2);
        books.put(b3.id, b3);
        books.put(b4.id, b4);

        books.values().stream().forEach(System.out::println);
        System.out.println();

        books.values().stream().forEach(b -> b.setQuantity(2 * b.quantity));
        books.values().stream().forEach(System.out::println);
        System.out.println();

        books.merge(233, books.get(233), (a, b) -> {
            a.publisher += " USA";
            return a;
        });
        books.values().stream().forEach(System.out::println);
        System.out.println();

    }
}

0 replies

preeti-max · 2022-03-08T06:03:47Z

preeti-max
Mar 8, 2022

package Collections;

import java.util.HashMap;

class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (id != other.id)
            return false;
        return true;
    }

    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

}

public class BookDriver {

    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

        HashMap<Integer, Book> books = new HashMap<>();

        books.put(b1.id, b1);
        books.put(b2.id, b2);
        books.put(b3.id, b3);
        books.put(b4.id, b4);

        books.values().stream().forEach(System.out::println);
        books.values().stream().forEach(i -> i.quantity *= 2

        );

        System.out.println("After doubling");
        books.values().stream().forEach(System.out::println);
        books.merge(233, books.get(233), (oldvalue, newvalue) -> {
            newvalue.publisher += " USA";
            return newvalue;
        });

        System.out.println("After merging");
        books.values().stream().forEach(System.out::println);

    }

}

0 replies

Amrit-Raj22 · 2022-03-08T06:05:18Z

Amrit-Raj22
Mar 8, 2022

package week5.day2;

import java.util.HashMap;
import java.util.Map;

class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result;
        result = prime + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (id != other.id)
            return false;
        return true;
    }

}

public class Books {
    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

        Map<Integer, Book> bookstore = new HashMap<>();
        bookstore.put(b1.id, b1);
        bookstore.put(b2.id, b2);
        bookstore.put(b3.id, b3);
        bookstore.put(b4.id, b4);

        for (Book b : bookstore.values()) {
            System.out.println(b);
        }
        for (Integer key : bookstore.keySet()) {
            Integer amt = bookstore.get(key).quantity * 2;
            bookstore.get(key).quantity = amt;
        }
        System.out.println();
        for (Book b : bookstore.values()) {
            System.out.println(b);
        }
        // bookstore.merge(233, bookstore.get(233), (oldval, newval)
        // ->newval.publisher+"USA");
        bookstore.merge(233, bookstore.get(233), (oldval, newval) -> {
            newval.publisher += "USA";
            return newval;
        });
        System.out.println();
        for (Book b : bookstore.values()) {
            System.out.println(b);
        }

    }

}

0 replies

rakeshGit419 · 2022-03-08T06:05:19Z

rakeshGit419
Mar 8, 2022

import java.util.*;

class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;
    
    public int getQuantity() {
        return quantity;
    }
    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }
    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }
    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((author == null) ? 0 : author.hashCode());
        result = prime * result + id;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        return result;
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;
        Book other = (Book) obj;
        if (author == null) {
            if (other.author != null) return false;
        } else if (!author.equals(other.author)) return false;
        if (id != other.id) return false;
        if (name == null) {
            if (other.name != null) return false;
        } else if (!name.equals(other.name)) return false;
        return true;
    }

}


public class BookDriver {
    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

        // List<Book> library = Arrays.asList(b1,b2,b3,b4);
        // library.forEach(System.out::println);

        // Set<Book> set = new HashSet<>();
        // Book b5 = null;
        // int maxQuant = 0;

        // for(int i=0;i<library.size();i++){
        //     for(int j=i+1;j<library.size();j++){
        //         if(library.get(i).equals(library.get(j))) set.add(library.get(i));
        //     }
        // }

        // for(Book b : library){
        //     if(!set.contains(b)){
        //         if(b.quantity > maxQuant){
        //             maxQuant = b.quantity;
        //             b5 = b;
        //         }
        //     }
        // }

        // System.out.println("No. of duplicate books = "+set.size());
        // set.forEach(System.out::println);
        // System.out.println(b5);
        HashMap<Integer,Book> books = new HashMap<>();
        books.put(121,b1);
        books.put(233,b2);
        books.put(101,b3);
        books.put(111,b4);

        for(Integer i : books.keySet()){
            System.out.println(books.get(i).toString());
        }

        for(Integer i : books.keySet()){
            int q = books.get(i).getQuantity();
            books.get(i).setQuantity(2*q);
        }

        books.merge(233,books.get(233),(v1,v2)->{v2.publisher = "Wiley USA";return v2;});
        System.out.println(books.get(233).toString());


    }
}

0 replies

SrideviYamala · 2022-03-08T06:05:59Z

SrideviYamala
Mar 8, 2022

package collections;

import java.util.HashMap;

class Book{
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (id != other.id)
            return false;
        return true;
    }

    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }
}
public class MapsTask {
    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
        HashMap<Integer, Book> books = new HashMap<Integer, Book>();
        books.put(b1.id, b1);
        books.put(b2.id, b2);
        books.put(b3.id, b3);
        books.put(b4.id, b4);
        for (Book value : books.values()) {
            System.out.println(value);
        }
        System.out.println("Updated Map: ");
        for (Book value : books.values()) {
            value.quantity *= 2;
            System.out.println(value);
        }
        System.out.println("Merge Function");
        books.merge(233, books.get(233),(oldValue,newValue) -> {
            newValue.publisher += " USA";
            return newValue;
        });
        System.out.println(books.get(233));
    } 
}

0 replies

shreiyarandive · 2022-03-08T06:07:21Z

shreiyarandive
Mar 8, 2022

package week6;

import java.util.HashMap;

class Book {
    protected int id;
    protected String name;
    protected String author;
    protected String publisher;
    protected int quantity;

    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }

    public int getQuantity() {
        return quantity;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }

    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((author == null) ? 0 : author.hashCode());
        result = prime * result + id;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (author == null) {
            if (other.author != null)
                return false;
        } else if (!author.equals(other.author))
            return false;
        if (id != other.id)
            return false;
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
        return true;
    }

}

public class HashMapBook {
    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

        HashMap<Integer, Book> books = new HashMap<>();
        books.put(b1.getId(), b1);
        books.put(b2.getId(), b2);
        books.put(b3.getId(), b3);
        books.put(b4.getId(), b4);

        books.values().stream().forEach(System.out::println);

        books.values().stream().forEach((book) -> book.setQuantity(2 * book.getQuantity()));

        System.out.println();
        System.out.println("After updating");
        books.values().stream().forEach(System.out::println);

        books.merge(233, books.get(233), (oldBook, newBook) -> {
            oldBook.publisher += " USA";
            return oldBook;
        });

        System.out.println();
        System.out.println("After merging");
        books.values().stream().forEach(System.out::println);

    }
}

0 replies

mkaifahmed · 2022-03-08T06:08:00Z

mkaifahmed
Mar 8, 2022

import java.util.*;


public class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (id != other.id)
            return false;
        return true;
    }

}




public class Main {
    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
        HashMap<Integer, Book> books = new HashMap<Integer, Book>();
        books.put(b1.id, b1);
        books.put(b2.id, b2);
        books.put(b3.id, b3);
        books.put(b4.id, b4);
        System.out.println("Orignial Values :");
        for (Book values : books.values()) {
            System.out.println(values);
        }
        System.out.println("Doubling the quantities :");
        books.forEach((k, v) -> {
            v.quantity *= 2;
            books.put(k, v);
            System.out.println(v);
        });
        books.merge(233, books.get(233), (a, b) -> {
            a.publisher += " USA";
            return a;
        });
        System.out.println("After merging : ");
        for (Book values : books.values()) {
            System.out.println(values);
        }
    }
}

0 replies

Shubhi27 · 2022-03-08T06:08:48Z

Shubhi27
Mar 8, 2022

package maps;

import java.util.HashMap;

class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (id != other.id)
            return false;
        return true;
    }

    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

}

public class BookDriver {
    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
        HashMap<Integer, Book> books = new HashMap<>();
        books.put(b1.id, b1);
        books.put(b2.id, b2);
        books.put(b3.id, b3);
        books.put(b4.id, b4);

        for (Book value : books.values()) {
            System.out.println(value);
        }

        books.values().stream().forEach(q -> q.quantity *= 2);
        System.out.println("After Doubling the quantity:");
        for (Book value : books.values()) {
            System.out.println(value);
        }

        books.merge(233, books.get(233), (oldValue, newValue) -> {
            newValue.publisher += " USA";
            return newValue;
        });
        System.out.println("After modifying publisher name:");
        books.values().stream().forEach(System.out::println);
    }

}

0 replies

KaminiJha · 2022-03-08T06:10:53Z

KaminiJha
Mar 8, 2022

package Map;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    // parameterised constructor
    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    // override equals()
    @Override
    public boolean equals(Object other) {
        if (this == other) {
            return true;
        } else if (other == null) {
            return false;
        } else if (this.getClass() != other.getClass())
            return false;
        Book obj = (Book) other;
        if (id != obj.id) {
            return false;
        } else {
            return true;
        }
    }

    // override hashCode()
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    // override toString()
    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

}

public class BooksMap {

    
    public static void main(String[] args) {

        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
        HashMap<Integer, Book> map = new HashMap<>();
        map.put(b1.id, b1);
        map.put(b2.id, b2);
        map.put(b3.id, b3);
        map.put(b4.id, b4);

        map.forEach((k, v) -> {
            v.quantity=2*v.quantity;
            System.out.println("key is " + k + " and value is " + v);
        });
        merge(map);

    }
public static void merge(Map<Integer,Book> map)
    {
        map.merge(233, map.get(233), (oldVal,newVal)->{
            newVal.publisher+="USA";
            return newVal;
        });
        // if(map.containsKey(233))
        // {
        //     map.get(233).publisher+="USA";
        // }
        System.out.println(map);
    }
}

0 replies

ratnadeepikavuddagiri · 2022-03-08T06:12:25Z

ratnadeepikavuddagiri
Mar 8, 2022

package JavaCollections.Maps;

import java.util.*;

class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;
    
    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }
    

    public int getId() {
        return id;
    }

    public int getQuantity() {
        return quantity;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }


    public String getPublisher() {
        return publisher;
    }


    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }


    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }


    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (id != other.id)
            return false;
        return true;
    }
}

public class BookDriverMap {
    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
        HashMap<Integer,Book> books = new HashMap<>();
        books.put(b1.getId(),b1);
        books.put(b2.getId(),b2);
        books.put(b3.getId(),b3);
        books.put(b4.getId(),b4);
        System.out.println("Initial Book Details");
        
        for(Book book : books.values())
            System.out.println(book);
        Iterator<Integer> iterator = books.keySet().iterator();
        System.out.println("Book Details after doubling the quantity");
        while(iterator.hasNext()){
            Integer key =iterator.next();
            Book book = books.get(key);
            int quantity = book.getQuantity();
            book.setQuantity(quantity*2);
            books.put(key,book);
        }
        for(Book book : books.values())
            System.out.println(book);

        books.merge(233,books.get(233),(oldBook,newBook) -> {
            String str =oldBook.getPublisher();
            newBook.setPublisher(str+" USA"); 
            return newBook;
        });
        System.out.println(books.get(233));
    
    }
}

0 replies

aish955 · 2022-03-08T06:12:48Z

aish955
Mar 8, 2022

`package JavaMaps;

import java.util.;
import java.util.jar.Attributes.Name;
import java.lang.;

class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

@Override
public String toString() {
    return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
            + quantity + "]";
}

@Override
public int hashCode() {
    int prime = 31;
    int result = 1;
    result = prime * result + id;
    return result;
}

@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    Book other = (Book) obj;
    if (id != other.id)
        return false;
    return true;
}

}

public class MapImplementation {
public static void main(String[] args) {
Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
Map<Integer, Book> books = new HashMap<>();
books.put(b1.id, b1);
books.put(b2.id, b2);
books.put(b3.id, b3);
books.put(b4.id, b4);

    books.forEach((k, v) -> {
        System.out.println(v);
    });

    books.forEach((k, v) -> v.quantity = v.quantity * 2);

    books.forEach((k, v) -> {
        System.out.println(v);
    });

    books.merge(233, books.get(233), (a, b) -> {
        b.publisher += " USA";
        return b;
    });

    books.forEach((k, v) -> {
        System.out.println(v);
    });

}

}
`

0 replies

Gaurav-Joshi-31 · 2022-03-08T06:16:12Z

Gaurav-Joshi-31
Mar 8, 2022

import java.util.HashMap;
import java.util.Map;

class Bookk {
    private int id;
    private String name;
    private String author;
    private String publisher;
    private int quantity;

    public Bookk(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }

    public int getQuantity() {
        return quantity;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Bookk other = (Bookk) obj;
        if (id != other.id)
            return false;
        return true;
    }

    @Override
    public String toString() {
        return "Bookk [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

}

public class BooksDriver {
    public static void main(String[] args) {
        Bookk b1 = new Bookk(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Bookk b2 = new Bookk(233, "Operating System", "Galvin", "Wiley", 6);
        Bookk b3 = new Bookk(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Bookk b4 = new Bookk(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
        Map<Integer, Bookk> map = new HashMap<>();
        map.put(b1.getId(), b1);
        map.put(b2.getId(), b2);
        map.put(b3.getId(), b3);
        map.put(b4.getId(), b4);
        map.values().stream().forEach(System.out::println);
        System.out.println("After updating quantity");

        map.values().stream().forEach(b -> b.setQuantity(2 * b.getQuantity()));
        map.values().stream().forEach(System.out::println);

        System.out.println("After merge function");

        map.merge(233, map.get(233), (a, b) -> {
            a.setPublisher(a.getPublisher() + "USA");
            return a;
        });

        map.values().stream().forEach(System.out::println);

    }
}

0 replies

VigneshVishwa · 2022-03-08T06:16:17Z

VigneshVishwa
Mar 8, 2022

package Maps;

import java.util.HashMap;

class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    @Override
    public int hashCode() {
        final int prime = 37;
        int result = 1;
        result = prime * result + ((author == null) ? 0 : author.hashCode());
        result = prime * result + id;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (id != other.id)
            return false;
        return true;
    }

    @Override
    public String toString() {
        return "[Author=" + author + ", Id=" + id + ", Name=" + name + ", Publisher=" + publisher + ", Quantity="
                + quantity + "]";
    }

}

public class MapMerge {

    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

        HashMap<Integer, Book> books = new HashMap<>();

        books.put(b1.id, b1);
        books.put(b2.id, b2);
        books.put(b3.id, b3);
        books.put(b4.id, b4);
        System.out.println("Contents of Book");
        books.values().stream().forEach(System.out::println);
        books.values().stream().forEach(i -> i.quantity *= 2

        );

        System.out.println("After doubling");
        books.values().stream().forEach(System.out::println);
        books.merge(233, books.get(233), (oldvalue, newvalue) -> {
            newvalue.publisher += " USA";
            return newvalue;
        });

        System.out.println("After merging");
        books.values().stream().forEach(System.out::println);

    }

}

0 replies

GantaGreeshma · 2022-03-08T06:16:54Z

GantaGreeshma
Mar 8, 2022

package collection_framework;

import java.util.*;

class Book {
    int id;
    String name;
    String author;
    String publisher;
    int quantity;

    public Book(int id, String name, String author, String publisher, int quantity) {
        this.id = id;
        this.name = name;
        this.author = author;
        this.publisher = publisher;
        this.quantity = quantity;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (id != other.id)
            return false;
        return true;
    }

    @Override
    public String toString() {
        return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
                + quantity + "]";
    }

}

public class BookMap {
    public static void main(String[] args) {
        Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
        Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
        Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
        Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
        HashMap<Integer, Book> books = new HashMap<>();
        books.put(b1.id, b1);
        books.put(b2.id, b2);
        books.put(b3.id, b3);
        books.put(b4.id, b4);
        for (Integer ele : books.keySet()) {
            System.out.println(ele + ":" + books.get(ele));
        }
        for (Integer ele : books.keySet()) {
            Integer res = books.get(ele).quantity * 2;
            books.get(ele).quantity = res;
            System.out.println(ele + ":" + books.get(ele));
        }
        // books.values().stream().forEach(i->i.quantity*=2);
        books.values().stream().forEach(System.out::println);
        books.merge(233, books.get(233), (oldvalue, newvalue) -> {
            newvalue.publisher += "usa";
            return newvalue;
        });
        books.values().stream().forEach(System.out::println);
    }
}

0 replies

akratimishra22 · 2023-09-26T15:06:19Z

akratimishra22
Sep 26, 2023

Files (1).zip

1 reply

akratimishra22 Sep 26, 2023

By Akrati Mishra

nitesh-shrivastava · 2023-09-26T15:08:30Z

nitesh-shrivastava
Sep 26, 2023

package MapsModule;

import java.util.*;

class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

public String getPublisher() {
    return publisher;
}

public void setPublisher(String publisher) {
    this.publisher = publisher;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public int getQuantity() {
    return quantity;
}

public void setQuantity(int quantity) {
    this.quantity = quantity;
}

@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + id;
    return result;
}

@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    Book other = (Book) obj;
    if (id != other.id)
        return false;
    return true;
}

@Override
public String toString() {
    return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
            + quantity + "]";
}

}

public class Bibliophiles {
public static void main(String[] args) {
Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
Map<Integer, Book> Books = new HashMap<>();
Books.put(b1.id, b1);
Books.put(b2.id, b2);
Books.put(b3.id, b3);
Books.put(b4.id, b4);
Books.values().stream().forEach(System.out::println);
System.out.println("Quantity Changed");
Books.values().stream().forEach((value) -> value.setQuantity(value.quantity * 2));
Books.values().stream().forEach(System.out::println);
System.out.println("Name changed");
Books.merge(233, Books.get(233), (oldValue, newValue) -> {
newValue.publisher += "USA";
return newValue;
});
Books.values().stream().forEach(System.out::println);
System.out.println();
System.out.println(Books.get(233));
}

}

0 replies

venkat316 · 2023-09-26T15:09:19Z

venkat316
Sep 26, 2023

`package EDU;

import java.util.Objects;

public class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public Book(int id,String name,String author,String publisher,int quantity)
{
    this.author=author;
    this.id=id;
    this.publisher= publisher;
    this.quantity=quantity;
    this.name=name;
}

@Override
public String toString() {
    return  "id=" + id +
            ", name='" + name +
            ", author='" + author +
            ", publisher='" + publisher +
            ", quantity=" + quantity;
}

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    Book book = (Book) o;
    return id == book.id && quantity == book.quantity && Objects.equals(name, book.name) && Objects.equals(author, book.author) && Objects.equals(publisher, book.publisher);
}

@Override
public int hashCode() {
    return Objects.hash(id, name, author, publisher, quantity);
}

}

package EDU;

import java.util.HashMap;
import java.util.Map;

public class Driver {
public static void main(String[] args) {
Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

    HashMap<Integer,Book> map = new HashMap<>();
    map.put(b1.id,b1);
    map.put(b2.id,b2);
    map.put(b3.id,b3);
    map.put(b4.id,b4);

    for( Map.Entry<Integer, Book> m: map.entrySet()){
        System.out.println(m.getValue().toString());
    }

    for( Map.Entry<Integer, Book> m: map.entrySet()){
        System.out.println(m.getValue());
    }

    for( Map.Entry<Integer, Book> m: map.entrySet()){
         m.getValue().quantity = m.getValue().quantity * 2;
    }

    map.merge(233,map.get(233),(a,b) ->{
        b.publisher +="USA";
        return b;
    });

    for( Map.Entry<Integer, Book> m: map.entrySet()){
        System.out.println(m.getValue());
    }


}

}
`

0 replies

arunesh-india · 2023-09-26T15:18:42Z

arunesh-india
Sep 26, 2023

src.zip
collection

0 replies

shukrasahu · 2023-09-26T15:22:10Z

shukrasahu
Sep 26, 2023

import java.util.Objects;
import java.util.Map;
import java.util.HashMap;
class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

@Override
public String toString() {
    return "Book [id=" + id + ",name=" + name + ",author=" + author +
        ",publisher=" + publisher + ",quantity=" + quantity + "]";
}

@Override
public int hashCode() {
    return Objects.hash(author, id, name, publisher, quantity);
}

@Override
public boolean equals(Object obj) {
    if(this == obj)
        return true;
    if(obj ==null)
        return false;
    if(getClass() != obj.getClass())
        return false;
    Book other = (Book) obj;
    return Objects.equals(author, other.author) && id == other.id
        && Objects.equals(name, other.name) && Objects.equals(publisher, other.publisher) && quantity == other.quantity;
}

}
class Driver {
public static void main(String[] args) {

    Book b1 = new Book(121, "Let us C", "Yahwant Kanetkar", "BPB", 8);
    Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
    Book b3 = new Book(101, "Data Communications and Networking", "Forouzan", "Mc Graw Hill", 4);
    Book b4 = new Book(121, "Let us C", "Yahwant Kanetkar", "Mc Graw Hill", 11);
    
    Map<Integer, Book> books = new HashMap<>();
    books.put(b1.id, b1);
    books.put(b2.id, b2);
    books.put(b3.id, b3);
    books.put(b4.id, b4);
    
    System.out.println("Displaying the books");
    
    books.values().stream().forEach(System.out::println);
    
    books.merge(233, books.get(233), (oldVal, newVal) -> {
        newVal.publisher += " USA";
        return newVal;
    });
    
    System.out.println("Updated details for Book Id 233 "+ books.get(233));
    
}

}

0 replies

Sourav21071998 · 2023-09-26T15:58:44Z

Sourav21071998
Sep 26, 2023

import java.util.HashMap;

class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + id;
    return result;
}

@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    Book other = (Book) obj;
    if (id != other.id ||name != other.name ||author != other.author ||publisher != other.publisher ||quantity != other.quantity)
        return false;
    return true;
}

@Override
public String toString() {
    return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
            + quantity + "]";
}

}

public class BookDriver {

public static void main(String[] args) {
    Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
    Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
    Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
    Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

    HashMap<Integer, Book> books = new HashMap<>();

    books.put(b1.id, b1);
    books.put(b2.id, b2);
    books.put(b3.id, b3);
    books.put(b4.id, b4);

    books.values().stream().forEach(System.out::println);
    books.values().stream().forEach(i -> i.quantity *= 2

    );

    System.out.println("After doubling");
    books.values().stream().forEach(System.out::println);
    books.merge(233, books.get(233), (oldvalue, newvalue) -> {
        newvalue.publisher += " USA";
        return newvalue;
    });

    System.out.println("After merging");
    books.values().stream().forEach(System.out::println);

}

}

0 replies

manideep-vv · 2023-09-26T16:26:33Z

manideep-vv
Sep 26, 2023

package edureka;

import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

public class Book {
int id;
String name;
String author;
String publisher;
int quantity;

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    Book book = (Book) o;
    return id == book.id;
}

public String getPublisher() {
    return publisher;
}

public void setPublisher(String publisher) {
    this.publisher = publisher;
}

@Override
public int hashCode() {
    return Objects.hash(id);
}

@Override
public String toString() {
    return "Book{" +
            "id=" + id +
            ", name='" + name + '\'' +
            ", author='" + author + '\'' +
            ", publisher='" + publisher + '\'' +
            ", quantity=" + quantity +
            '}';
}

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

public static void main(String[] args) {
    Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
    Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
    Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
    Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

    Map<Integer, Book> books = new HashMap<>();
    books.put(b1.id,b1);
    books.put(b2.id,b2);
    books.put(b3.id,b3);
    books.put(b4.id,b4);

    System.out.println(books);

    //Double the quantity of all the books.
    books.entrySet().forEach(e->{
        Book existingBookWithOldQty = e.getValue();
        existingBookWithOldQty.quantity*=2;
    });
    System.out.println("books with new quantity \n"+books);
    if(books.containsKey(233)){
        Book book233 = books.get(233);
        String pub = book233.getPublisher();
        book233.setPublisher("USA"+pub);
    }
    System.out.println("books after modifying for 233 \n"+books);
}

}

0 replies

hpsingh546 · 2023-09-26T16:55:11Z

hpsingh546
Sep 26, 2023

`// Online Java Compiler
// Use this editor to write, compile and run your Java code online
import java.util.HashMap;

class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
this.id = id;
this.name = name;
this.author = author;
this.publisher = publisher;
this.quantity = quantity;
}

@OverRide
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + id;
return result;
}

@OverRide
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Book other = (Book) obj;
if (id != other.id ||name != other.name ||author != other.author ||publisher != other.publisher ||quantity != other.quantity)
return false;
return true;
}

@OverRide
public String toString() {
return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
+ quantity + "]";
}}
class BookDriver {

public static void main(String[] args) {
Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

HashMap<Integer, Book> books = new HashMap<>();

books.put(b1.id, b1);
books.put(b2.id, b2);
books.put(b3.id, b3);
books.put(b4.id, b4);

books.values().stream().forEach(System.out::println);
books.values().stream().forEach(i -> i.quantity *= 2

);

System.out.println("After doubling");
books.values().stream().forEach(System.out::println);
books.merge(233, books.get(233), (oldvalue, newvalue) -> {
    newvalue.publisher += " USA";
    return newvalue;
});

System.out.println("After merging");
books.values().stream().forEach(System.out::println);

}}`

0 replies

MusinadaAnkitha · 2023-09-26T16:58:06Z

MusinadaAnkitha
Sep 26, 2023

import java.util.HashMap;
import java.util.*;

class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public String getPublisher() {
	return publisher;
}
public void setPublisher(String publisher) {
	this.publisher = publisher;
}
public Book(int id, String name, String author, String publisher, int quantity) {
	super();
	this.id = id;
	this.name = name;
	this.author = author;
	this.publisher = publisher;
	this.quantity = quantity;
}
@Override
public String toString() {
	return "Book [id=" + id + ", name=" + name + ", author=" + author + ", publisher=" + publisher + ", quantity="
			+ quantity + "]";
}
@Override
public int hashCode() {
	int prime = 31;
    int result = 1;
    result = prime * result + id;
    return result;
}
@Override
public boolean equals(Object obj) {
	if (this == obj)
		return true;
	if (obj == null)
		return false;
	if (getClass() != obj.getClass())
		return false;
	Book other = (Book) obj;
	return Objects.equals(author, other.author) && id == other.id && Objects.equals(name, other.name)
			&& Objects.equals(publisher, other.publisher) && quantity == other.quantity;
}

}

public class Main {
public static void main(String[] args) {
Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
HashMap<Integer, Book> books = new HashMap<Integer, Book>();
books.put(b1.id, b1);
books.put(b2.id, b2);
books.put(b3.id, b3);
books.put(b4.id, b4);
books.entrySet().forEach(b -> System.out.println(b));
books.values().stream().forEach(e -> e.quantity*=2);
System.out.println();
books.entrySet().forEach(e -> System.out.println(e));
merge(books,b2);
System.out.println();
books.values().forEach(e -> System.out.println(e));
}
public static void merge(HashMap<Integer, Book> books,Book b2) {
Optional first = books.values().stream().filter(e -> e.id==233).map(e -> e.publisher+=" USA").findFirst();
b2.setPublisher(first.get());
}
}

0 replies

BhavyasriGrandhi · 2023-09-26T17:10:37Z

BhavyasriGrandhi
Sep 26, 2023

package collections;

import java.util.HashMap;

class Book {
protected int id;
protected String name;
protected String author;
protected String publisher;
protected int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

@Override
public String toString() {
    return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
            + quantity + "]";
}

@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + id;
    return result;
}

@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    Book other = (Book) obj;
    if (id != other.id)
        return false;
    return true;
}

public int getQuantity() {
    return quantity;
}

public void setQuantity(int quantity) {
    this.quantity = quantity;
}

}

public class BookDriver {
public static void main(String[] args) {

    Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
    Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
    Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
    Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

    HashMap<Integer, Book> books = new HashMap<>();
    books.put(b1.id, b1);
    books.put(b2.id, b2);
    books.put(b3.id, b3);
    books.put(b4.id, b4);

    books.values().stream().forEach(System.out::println);
    System.out.println();

    books.values().stream().forEach(b -> b.setQuantity(2 * b.quantity));
    books.values().stream().forEach(System.out::println);
    System.out.println();

    books.merge(233, books.get(233), (a, b) -> {
        a.publisher += " USA";
        return a;
    });
    books.values().stream().forEach(System.out::println);
    System.out.println();

}

}

0 replies

jay4tech · 2023-09-27T04:47:52Z

jay4tech
Sep 27, 2023

@akash-coded
Name - Jay Prakash Kumar
Description - Implemented the discussion numbers 51, 56 and 61

core-java.zip

0 replies

arghyagiri · 2023-09-27T14:25:05Z

arghyagiri
Sep 27, 2023

@akash-coded : Below is the solution.

package demo.practice;

import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

public class BookMap {
public static void main(String[] args) {

    Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
    Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
    Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
    Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

    //Create a HashMap<Integer, Book> called books and insert all the book objects as values using their id  as the key.
    Map<Integer, Book> bookMap = new HashMap<>();
    bookMap.put(b1.getId(), b1);
    bookMap.put(b2.getId(), b2);
    bookMap.put(b3.getId(), b3);
    bookMap.put(b4.getId(), b4);

    //After insertion of all books, display all the values stored in books.
    System.out.println(bookMap);

    //Double the quantity of all the books.
    bookMap.forEach((k,v) -> v.setQuantity(v.getQuantity() * 2));
    System.out.println(bookMap);

    //Write a merge() function to check if a book with the id 23 3 exists or not. If it does, add " USA" to its publisher name
    bookMap.merge(233, bookMap.get(233), (oldBook, newBook) -> {
        newBook.setPublisher(newBook.getPublisher() + " USA");
        return newBook;
    });
    System.out.println(bookMap);
}

}
class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getAuthor() {
    return author;
}

public void setAuthor(String author) {
    this.author = author;
}

public String getPublisher() {
    return publisher;
}

public void setPublisher(String publisher) {
    this.publisher = publisher;
}

public int getQuantity() {
    return quantity;
}

public void setQuantity(int quantity) {
    this.quantity = quantity;
}

@Override
public String toString() {
    return "Book{" +
            "id=" + id +
            ", name='" + name + '\'' +
            ", author='" + author + '\'' +
            ", publisher='" + publisher + '\'' +
            ", quantity=" + quantity +
            '}';
}

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    Book book = (Book) o;
    return id == book.id && quantity == book.quantity && Objects.equals(name, book.name) && Objects.equals(author, book.author) && Objects.equals(publisher, book.publisher);
}

@Override
public int hashCode() {
    return Objects.hash(id, name, author, publisher, quantity);
}

}

0 replies

tarusoft531 · 2023-09-27T16:27:50Z

tarusoft531
Sep 27, 2023

import java.util.*;

class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

@Override
public int hashCode() {
    return Objects.hash(id, name, author, publisher, quantity);
}

@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null || getClass() != obj.getClass())
        return false;
    Book otherBook = (Book) obj;
    return id == otherBook.id && Objects.equals(name, otherBook.name)
            && Objects.equals(author, otherBook.author)
            && Objects.equals(publisher, otherBook.publisher)
            && quantity == otherBook.quantity;
}

@Override
public String toString() {
    return "Book [id=" + id + ", name=" + name + ", author=" + author + ", publisher=" + publisher + ", quantity="
            + quantity + "]";
}

}

public class Main {
public static void main(String[] args) {
// Create Book instances
Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

    // Create a HashMap to store books
    HashMap<Integer, Book> books = new HashMap<>();

    // Insert books into the HashMap using their id as the key
    books.put(b1.id, b1);
    books.put(b2.id, b2);
    books.put(b3.id, b3);
    books.put(b4.id, b4);

    // Display all the values stored in books
    for (Map.Entry<Integer, Book> entry : books.entrySet()) {
        System.out.println(entry.getValue());
    }

    // Double the quantity of all the books
    for (Book book : books.values()) {
        book.quantity *= 2;
    }

    // Write a merge() function to check if a book with id 233 exists and add " USA" to its publisher
    merge(books, 233, " USA");

    // Display all the values stored in books after the quantity update and merge
    System.out.println("\nAfter updating quantities and merging:");
    for (Map.Entry<Integer, Book> entry : books.entrySet()) {
        System.out.println(entry.getValue());
    }
}

public static void merge(HashMap<Integer, Book> books, int id, String suffix) {
    Book book = books.get(id);
    if (book != null) {
        book.publisher += suffix;
    }
}

}

0 replies

vysaga9 · 2023-09-27T18:07:17Z

vysaga9
Sep 27, 2023

`import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

class Book {
int id;
String name;
String author;
String publisher;
int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

public int getId() {
	return id;
}

public void setId(int id) {
	this.id = id;
}

public String getName() {
	return name;
}

public void setName(String name) {
	this.name = name;
}

public String getAuthor() {
	return author;
}

public void setAuthor(String author) {
	this.author = author;
}

public String getPublisher() {
	return publisher;
}

public void setPublisher(String publisher) {
	this.publisher = publisher;
}

public int getQuantity() {
	return quantity;
}

public void setQuantity(int quantity) {
	this.quantity = quantity;
}

@Override
public String toString() {
	return "Book [id=" + id + ", name=" + name + ", author=" + author + ", publisher=" + publisher + ", quantity="
			+ quantity + "]";
}

@Override
public int hashCode() {
	return Objects.hash( id, name, publisher, quantity,author);
}

@Override
public boolean equals(Object obj) {
	if (this == obj)
		return true;
	if (obj == null)
		return false;
	if (getClass() != obj.getClass())
		return false;
	Book other = (Book) obj;
	return id == other.id && Objects.equals(name, other.name)
			&& Objects.equals(publisher, other.publisher) && quantity == other.quantity && Objects.equals(author, other.author) ;
}

}

public class Bookdriver {
public static void main(String args[]) {

	Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
	Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
	Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
	Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);
	
	
	 Map<Integer, Book> books = new HashMap<>();
	 books.put(b1.getId(), b1);
	 books.put(b2.getId(), b2);
	 books.put(b3.getId(), b3);
	 books.put(b4.getId(), b4);

	 
	 for (Integer b: books.keySet()) {
		    Book book = books.get(b);
		    System.out.println(book);
		}
	 
	 books.forEach((k,v) -> v.setQuantity(v.getQuantity() * 2));
	    System.out.println(books);
	    
	    
	    books.merge(233, books.get(233), (oldBook, newBook) -> {
	        newBook.setPublisher(newBook.getPublisher() + " USA");
	        return newBook;
	    });
	    System.out.println(books);
}

}
`

0 replies

nmokariya25 · 2023-09-28T18:44:03Z

nmokariya25
Sep 28, 2023

package collections;

import java.util.HashMap;

class Book {
protected int id;
protected String name;
protected String author;
protected String publisher;
protected int quantity;

public Book(int id, String name, String author, String publisher, int quantity) {
    this.id = id;
    this.name = name;
    this.author = author;
    this.publisher = publisher;
    this.quantity = quantity;
}

@Override
public String toString() {
    return "Book [author=" + author + ", id=" + id + ", name=" + name + ", publisher=" + publisher + ", quantity="
            + quantity + "]";
}

@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + id;
    return result;
}

@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    Book other = (Book) obj;
    if (id != other.id)
        return false;
    return true;
}

public int getQuantity() {
    return quantity;
}

public void setQuantity(int quantity) {
    this.quantity = quantity;
}

}

public class BookStats {
public static void main(String[] args) {

    Book b1 = new Book(121, "Let us C", "Yashwant Kanetkar", "BPB", 8);
    Book b2 = new Book(233, "Operating System", "Galvin", "Wiley", 6);
    Book b3 = new Book(101, "Data Communications & Networking", "Forouzan", "Mc Graw Hill", 4);
    Book b4 = new Book(121, "Let us C", "Yashwant Kanetkar", "Mc Graw Hill", 11);

    HashMap<Integer, Book> books = new HashMap<>();
    books.put(b1.id, b1);
    books.put(b2.id, b2);
    books.put(b3.id, b3);
    books.put(b4.id, b4);

    books.values().stream().forEach(System.out::println);
    System.out.println();

    books.values().stream().forEach(b -> b.setQuantity(2 * b.quantity));
    books.values().stream().forEach(System.out::println);
    System.out.println();

    books.merge(233, books.get(233), (a, b) -> {
        a.publisher += " USA";
        return a;
    });
    books.values().stream().forEach(System.out::println);
    System.out.println();

}

}

0 replies

Task - Collections - Map Basics - Book Map #51

Uh oh!

Uh oh!

akash-coded Mar 8, 2022 Maintainer

A Map for Bibliophiles

Replies: 61 comments · 1 reply

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Uh oh!

Uh oh!

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Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

akash-coded
Mar 8, 2022
Maintainer

Replies: 61 comments 1 reply