ArrayIndexOutOfBoundsException

What causes this error

The index used to access the array is outside the valid range [0, array.length - 1]. This can happen in loops with off-by-one errors, when using user input as indices, or when arrays are shorter than expected.

How to fix it

Check the array length before accessing elements. Fix loop bounds to use < array.length instead of <= array.length. Validate user input before using it as an index.

int[] arr = {1, 2};
arr[5]; // AIOOBE