java.lang.ArrayIndexOutOfBoundsException

Question

I wrote some code in java:

  public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.println("Enter size of array:");
		int size = sc.nextInt();
		int[] intArray = new int[size];
		for (int i = 0; i < size; i++) {
			System.out.println("Please enter int value at index " + i + ":");
			intArray[i] = sc.nextInt();
		}
		System.out.println("Enter array index to get the value:");
		int index = sc.nextInt();
		sc.close();

		System.out.println("Value at " + index + " = " + intArray[index]);

But it gives me error:

 Enter size of int array:
     3
     Please enter int value at index 0:
     1
    Please enter int value at index 1:
     2
    Please enter int value at index 2:
    3
   Enter array index to get the value:
    4
   Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
   at com.journaldev.exceptions.ArrayIndexOutOfBoundsExceptionExample.main(ArrayIndexOutOfBoundsExceptionExample.java:23)

What is the problem in my code and why am I getting this kind of error?

Answer 1

java.lang.ArrayIndexOutOfBoundsException is a runtime exception, so it’s a unchecked exception and don’t need to be thrown explicitly from method.The code snippet below shows the small change in program while taking user input to access the element, if value is passed invalid then a warning message is shown to pass the valid value.

   boolean exit = false;
     while (!exit) {
	System.out.println("Enter array index to get the value:");
	int index = sc.nextInt();
	if (index < 0 || index >= size) {
		System.out.println("Valid index range is from 0 to " + (size - 1));
	} else {
		System.out.println("Value at " + index + " = " + intArray[index]);
		exit = true; //to terminate the program
		sc.close(); //close resources
	}
     }

So this is how we avoid getting ArrayIndexOutOfBoundsException in our program