Question

Write a java program that creates an integer array with 50 random values, prompts the user to enter the index of an element in the array between 0 and 49, then displays the corresponding element value. If the specified index is out of bounds, display an error message (e.g. “Out of Bounds”) and ask the user to enter another index. Use a while loop that will keep prompting the user until a valid input is received. To handle invalid inputs, write two versions of your program: one that uses exception handling, and one that uses defensive programming. Assume a user will always enter numbers. Verify that the displayed element number is indeed from the index number entered. Add comments.

Sample run:

list[50] of random int generated

14 37 19 98 31 1 68 11 18 90

36 14 37 63 68 54 64 51 80 75

66 85 30 65 97 66 87 47 52 63

9 22 68 70 11 32 23 69 37 12

62 62 76 89 33 0 43 87 30 27

Enter an index: 55

Out of Bound. Try again:50

Out of Bound. Try again:5

The element is 1

Answer 1

Dear student your solution is below:

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Note: Follow the screenshot of program to get the idea about indentation in program.

Comment are written in front of code for better understability of the program.

First program is based on defensive approac.

Second Program uses Exception Handling

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1. Program in Java: (Defensive Approach)

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//importing the classes
import java.util.Random;
import java.util.Scanner;

//class
public class Main
{
   //main function
   public static void main(String[] args) {
  
       int list[] = new int[50]; //declearing a list of size 50
       Random r = new Random(); //for generating random number
       Scanner sc = new Scanner(System.in);
       for(int i = 0; i < 50; i++){
       list[i] = r.nextInt(100); //generating and storing random number in list
       }
      
       int index = -1;
       System.out.print("Enter an Index: "); //input index from user
       index = sc.nextInt();
      
       //checking and taking input again from user
       while(index < 0 || index > 49){
       System.out.print("Out of Bound. Try Again: ");
       index = sc.nextInt();
       }
      
       sc.close();
       //printing the element at provided index
       System.out.println("The element is " + list[index]);
   }
}// End of program

OUTPUT:

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2. Java Program (Exception Handling):

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//importing the classes
import java.util.Random;
import java.util.Scanner;

//class
public class Main
{
   //main function
   public static void main(String[] args) {
  
       int list[] = new int[50]; //declearing a list of size 50
       Random r = new Random(); //for generating random number
       Scanner sc = new Scanner(System.in);
       for(int i = 0; i < 50; i++){
       list[i] = r.nextInt(100); //generating and storing random number in list
       }
      
       int index = -1;
       System.out.print("Enter an Index: "); //input index from user
       index = sc.nextInt();
      
       //checking and taking input again from user with try-catch
       while(true){
       try{
       //printing the element at provided index
       System.out.println("The element is " + list[index]);
      
       //if no exception occour in above statement
       // then break out of the while loop
      
       break;
      
       }catch(ArrayIndexOutOfBoundsException e){
      
       //If exception occour in try block
       System.out.print("Out of Bound. Try Again: ");
       index = sc.nextInt();
       }
       }
   }
}

OUTPUT:

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Hope it has helped you.

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