Homework lessons 1.

lessons1/src/Digits.java

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+
+public class Digits {
+    private static final String[] word = {"Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine"};
+
+    public static void toWord(int digit){
+        try {
+            System.out.println(digit + " - " + word[digit]);
+        }
+        catch (IndexOutOfBoundsException e){
+            System.out.println("Number is not a digit");
+        }
+    }
+}

lessons1/src/Factorial.java

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+
+public class Factorial {
+
+    private static final int MAX_NUMBER = 20;
+
+    public static long getFactorial(int number){
+        if(number > MAX_NUMBER) {
+            System.out.println("Number must be in the range [0, " + MAX_NUMBER +"].");
+        }
+        else if(number <  0){
+            System.out.println("Number must be positive");
+        }
+        else{
+            return calculateFactorial(number);
+        }
+        return 0;
+    }
+
+    private static long calculateFactorial(int number){
+        if(number == 0){
+            return 1;
+        }
+        else {
+            return number * calculateFactorial(number - 1);
+        }
+    }
+}

lessons1/src/FibonacciSequence.java

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+
+public class FibonacciSequence {
+    private  int[] fibonacciSequence;
+
+    FibonacciSequence(int sequenceLength){
+        fibonacciSequence = new int[sequenceLength];
+        create();
+    }
+
+    private void create(){
+        fibonacciSequence[0] = 1;
+        fibonacciSequence[1] = 1;
+
+        for(int i = 2; i < fibonacciSequence.length; i++){
+            fibonacciSequence[i] = fibonacciSequence[i - 1] + fibonacciSequence[i - 2];
+        }
+    }
+
+    public void outputFibonacciSequence(){
+        System.out.print("First " + fibonacciSequence.length + " fibonacci number: ");
+        for(int fibonacciNumber : fibonacciSequence){
+            System.out.print(fibonacciNumber + " ");
+        }
+        System.out.println();
+    }
+
+    public int[] getFibonacciSequence() {
+        return fibonacciSequence;
+    }
+}
+
+

lessons1/src/Main.java

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+import java.util.Scanner;
+
+public class Main {
+
+    public static void main(String args[]){
+        Scanner scanner = new Scanner(System.in);
+        String menu = "\nEnter number to select operation " +
+                "\n  1. Calculate the factorial " +
+                "\n  2. Output the Fibonacci sequence " +
+                "\n  3. Convert digit to word" +
+                "\n Press another number for exit";
+
+        while(true){
+            System.out.println(menu);
+            switch (scanner.nextInt()){
+                case 1:
+                    System.out.print("Enter the number in the range [0, 20]: ");
+                    int number = scanner.nextInt();
+                    System.out.println(number + "! = " + Factorial.getFactorial(number));
+                    break;
+                case 2:
+                    System.out.print("Enter the size of Fibonacci sequence: ");
+                    new FibonacciSequence(scanner.nextInt()).outputFibonacciSequence();
+                    break;
+                case 3:
+                    System.out.print("Enter the digits: ");
+                    Digits.toWord(scanner.nextInt());
+                    break;
+                default:
+                    System.exit(0);
+            }
+        }
+    }
+}