HomeTaskWeek1 (Java basics)

src/com/geekhub/java/lessons/CalculatorFactorial.java

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+package com.geekhub.java.lessons;
+
+import com.geekhub.java.lessons.exceptions.FactorialOfNegativeNumberException;
+
+public class CalculatorFactorial {
+
+    public int getFactorial(int n) throws FactorialOfNegativeNumberException{
+
+        if (n < 0) throw new FactorialOfNegativeNumberException();
+
+        if (n == 0) return 1;
+
+        return n * getFactorial(n - 1);
+    }
+}

src/com/geekhub/java/lessons/CalculatorFibonacci.java

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+package com.geekhub.java.lessons;
+
+public class CalculatorFibonacci {
+
+    public int[] getFibonacci(int n) {
+
+        if (n <= 0) return new int[0];
+
+        int [] fib = new int[n];
+
+        fib[0] = 1;
+        if (n>1) {
+            fib[1] = 1;
+        }
+
+        for (int i = 2; i < fib.length; i++) {
+            fib[i] = fib[i-2]+fib[i-1];
+        }
+
+        return fib;
+    }
+}

src/com/geekhub/java/lessons/Main.java

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+package com.geekhub.java.lessons;
+
+import com.geekhub.java.lessons.exceptions.FactorialOfNegativeNumberException;
+import com.geekhub.java.lessons.exceptions.NotNumberException;
+
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class Main {
+
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        int n = 0;
+        int menuItem;
+        boolean run = true;
+        while (run) {
+            printMenu();
+            if (in.hasNextInt()) {
+                menuItem = in.nextInt();
+
+                switch (menuItem) {
+                    case 1:
+                        CalculatorFactorial calculatorFactorial = new CalculatorFactorial();
+                        try {
+                            System.out.println("input n:");
+                            n = in.nextInt();
+                            System.out.println(n + "! = " + calculatorFactorial.getFactorial(n));
+                        } catch (FactorialOfNegativeNumberException e) {
+                            System.out.println("error: factorial of negative number");
+                        }
+                        break;
+                    case 2:
+                        System.out.println("input n:");
+                        n = in.nextInt();
+                        CalculatorFibonacci calculatorFibonacci = new CalculatorFibonacci();
+                        int[] sequenceFib = calculatorFibonacci.getFibonacci(n);
+                        System.out.println("sequence " + n + " number(s) fibonacci:");
+                        System.out.println(Arrays.toString(sequenceFib));
+                        break;
+                    case 3:
+                        System.out.println("input number:");
+                        n = in.nextInt();
+                        NumberToWord memberToWord = new NumberToWord();
+                        try {
+                            System.out.println(n + " converted to " + memberToWord.toWord(n));
+                        } catch (NotNumberException e) {
+                            System.out.println("value is not number");
+                        }
+                        break;
+                    default:
+                        run = false;
+                }
+            } else run = false;
+        }
+    }
+
+    private static void printMenu() {
+        System.out.println("==== Menu: ====");
+        System.out.println("1 - calculate factorial");
+        System.out.println("2 - calculate fibonacci");
+        System.out.println("3 - number to word convert");
+        System.out.println("any other symbol - exit");
+        System.out.println("===============");
+        System.out.println("select menu item:");
+    }
+}

src/com/geekhub/java/lessons/NumberToWord.java

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+package com.geekhub.java.lessons;
+
+import com.geekhub.java.lessons.exceptions.NotNumberException;
+
+public class NumberToWord {
+
+    public String toWord(int n) throws NotNumberException {
+
+        switch (n) {
+            case 0:
+                return "zero";
+            case 1:
+                return "one";
+            case 2:
+                return "two";
+            case 3:
+                return "three";
+            case 4:
+                return "four";
+            case 5:
+                return "five";
+            case 6:
+                return "six";
+            case 7:
+                return "seven";
+            case 8:
+                return "eight";
+            case 9:
+                return "nine";
+            default:
+                throw new NotNumberException();
+        }
+    }
+}

src/com/geekhub/java/lessons/exceptions/FactorialOfNegativeNumberException.java

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+package com.geekhub.java.lessons.exceptions;
+
+public class FactorialOfNegativeNumberException extends Exception {
+}

src/com/geekhub/java/lessons/exceptions/NotNumberException.java

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+package com.geekhub.java.lessons.exceptions;
+
+public class NotNumberException extends Exception {
+}