SafeArrayLookup.java

/*
Rahim Siddiq
May 26 2023
ArrayIndexOutOfBoundsException
*/

import java.util.Random;
import java.util.Scanner;
import java.util.InputMismatchException;

public class SafeArrayLookup
{
	public static void main(String[] args)
	{
		// Program variables. Create array to store 100 elements, variable to store index and a boolean for validInput
		int[] randomArray = new int[100];
		int index = 0;
		boolean validInput = false;
		
		// Description of program for the user
		System.out.println("========================================================================");
        System.out.println("===== Program creates an array of 100 elements with random values ======");
        System.out.println("== displays the value of elements in the specified index of the array ==");
		System.out.println("========================================================================");
        System.out.println();
		
		// Create random object and use a for-loop to populate the elements of randomArray
		Random rand = new Random();
		for (int i = 0; i < randomArray.length; i++)
		{
			randomArray[i] = rand.nextInt(100);
		}
		
		// Create a new scanner object for user input
		Scanner input = new Scanner(System.in);
	
		while (!validInput) // will re-prompt for input if incorrect 
        {
            try
            {
                System.out.print("Enter a number for index to see it's value [0-99]: ");
                index = input.nextInt();
                System.out.println("The element found at index " + index + " is: " + randomArray[index]);
                // Changes condition to break while loop
                validInput = true;
            }
            // ArrayIndexOutOfBoundsException catches errors if index is out of range
            catch(ArrayIndexOutOfBoundsException rangeEx)
            {
                System.out.println("The number entered is outside the bounds of the index, please try again");
                System.out.println();
            }
            // Catches errors caused by non-integer inputs
            catch(InputMismatchException typeEx)
            {
                System.out.println("You must enter an integer for index number, please try again");
                System.out.println();
                // Clears scanner buffer of non-int input
                input.nextLine();
            }
        }
        // Close the scanner
        input.close();
	}
}