Question

Write a JAVA program with methods that initializes an array with 20 random integers between 1 and 50 and then prints four lines of output, containing

1)The initialized array.

2)Every element at an even index.

3)Every even element.

4)All elements in reverse order.

Requirements (and hints):

1. Build a method that takes any integer array as input and prints the elements of the array. ALL printing in this lab must be done using a call to the printArray method and you should only have one method that prints an array. Think through how to structure the method header and how to call this method. You can reuse the logic for the actual printing of an array (from Lab11b) or use a textbook example. The difficulty in this lab is thinking through how the array is passed each time. Keep in mind your printArray method should be generic enough to print any integer array that is passed to it.

2. Each of the bullets above should be a separate method. Think through how to name your method, what should be in the method header, how to call each of these methods and what if anything should be passed and returned. Realize that each of your methods might need to call the printArray method to accomplish the printing of the array.

3. The original array must be retained and reused by each of the methods you build. For this reason, think through how you will retain a copy of the original array to be reused each time one of your methods has altered the original array. (Hint: you could use Arrays.copyOf)

4. The main method should be basically a series of calls to your methods.

5. NO keyboard input for this lab.

Answer 1

import java.util.Random;

public class ManipulateArray {

  

   static void printArray(int arr[]){

       for (int i = 0; i < arr.length; ++i)

           System.out.print(arr[i]+ " ");

       System.out.println();

   }

  

   static void printEvenIndex(int arr[]){

       for (int i = 0; i < arr.length; ++i) {

           if(i%2==0)

           System.out.print(arr[i]+ " ");

       }

       System.out.println();

   }

   static void printEvenNumbers(int arr[]){

       for (int i = 0; i < arr.length; ++i) {

           if(arr[i]%2==0)

           System.out.print(arr[i]+ " ");

       }

       System.out.println();

   }

  

   static void printReverseArray(int arr[]){

       for (int i = arr.length-1; i>=0; --i)

           System.out.print(arr[i]+ " ");

       System.out.println();

   }

   public static void main(String[] args) {

Random r = new Random();

       int arr[] = new int[20];

       for(int i=0; i<20;++i)

           arr[i] = r.nextInt(50) + 1;

       System.out.println("Original Array: ");

       printArray(arr);

      

       System.out.println("Even Index of Array: ");

       printEvenIndex(arr);

      

       System.out.println("Evn numbers of Array: ");

       printEvenNumbers(arr);

      

       System.out.println("reverse Array: ");

       printReverseArray(arr);

      

      

   }

}
===============================================
See Output


Console 3 <terminated> ManipulateArray [Java Application] /Library/Internet Plug-Ins/JavaAppl Original Array: 20 49 3 6 26 33 5 36 21 33 47 22 44 12 7 40 1 42 50 33 Even Index of Array: 20 3 26 5 21 47 44 7150 Evn numbers of Array: 20 6 26 36 22 44 12 40 42 50 reverse Array: 33 50 42 1 40 7 12 44 22 47 33 21 36 5 33 26 6 3 49 20 ManipulateArryAllCode Solution.java 99 107 108 109 110 112 113 114 115 116 118 119 120 121 122 123 124 125 126 127 128 Random rnew Random); int arr[] = new int [20]; for(int i-0 <20;++i) arrilr.nextInt(50) + 1; System.out.printlnC"Original Array: ; printArray(arr); System.out.println"Even Index of Array: "); printEvenIndex(arr); 129 130 System.out.printlnC" Evn numbers of Array: "; printEvenNumbers(arr); 131 132 133 134 System.out.println("reverse Array: "); printReverseArrayCarr); 135 136 137 138 139
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