ArrayIndexOutOfBoundsException in Java

The ArrayIndexOutOfBoundsException occurs whenever we are trying to access any item of an array at an index which is not present in the array. In other words, the index may be negative or exceed the size of an array.

The ArrayIndexOutOfBoundsException is a subclass of IndexOutOfBoundsException, and it implements the Serializable interface.

Example of ArrayIndexOutOfBoundsException

public class ArrayIndexOutOfBoundException {

	public static void main(String[] args) {
String[] arr = {"Rohit","Shikar","Virat","Dhoni"}; 
//Declaring 4 elements in the String array                                     
		
		for(int i=0;i<=arr.length;i++) {		

//Here, no element is present at the iteration number arr.length, i.e 4
	         System.out.println(arr[i]);    
//So it will throw ArrayIndexOutOfBoundException at iteration 4			
		}

	}

}

Output:

Constructors of ArrayIndexOutOfBoundsException

The following types of ArrayIndexOutOfBoundException constructors are -

Constructors	Description
ArrayIndexOutOfBoundsException()	It constructs ArrayIndexOutOfBoundsException with no details being showed up in the console.
ArrayIndexOutOfBoundsException(int index)	It constructs ArrayIndexOutOfBoundsException with the index variable indicating the index which is illegal
ArrayIndexOutOfBoundsException(String s)	It constructs ArrayIndexOutOfBoundsException with specified detail message.

How to avoid ArrayIndexOutOfBoundsException

One of the biggest issues due to which ArrayIndexOutOfBoundsException occurs is that the indexing of array starts with 0 and not 1 and the last element is at the array length -1 index, due to which, users commonly make a mistake while accessing the elements of the array.
Always take care while making the starting and end conditions of the loop.
If stuck with any such exception, try to debug the code.
Using an enhanced for loop
- An enhanced for loop is the one which iterates over contiguous memory allocation and iterates only on legal indexes.
  For example:-

public class ArrayIndexOutOfBoundException {

public static void main(String[] args) {
	ArrayList<String> listOfPlayers = new ArrayList<>();
	listOfPlayers.add("Rohit");
	listOfPlayers.add("Shikhar");
	listOfPlayers.add("Virat");
	listOfPlayers.add("Dhoni");
	for(String val : listOfPlayers){
	System.out.println("Player Name: "+val);
	}


	}
}

Using a type-safe Iterator
- Type-safe iterators don't throw an exception when they are iterating over a collection and making changes to it as they make a snapshot of the collection and make the changes to it. For example-

HashMap<Integer,Integer> map = new HashMap<>();
map.put(1,1);
map.put(2,2);
map.put(3,3);
map.put(4,4);

final Iterator<Integer> it = map.Keyset().iterator();
for (int i = 0; it.hasNext(); i++)
{
    System.out.println(it.next());
}

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