Question

I expected this to compile, but I kept getting the error “The type of an expression must be an array type, but it is resolved to Object”. Is there a simple workaround for this?

public class NodeTest {
    public static void main(String[] args) {

    Object[] arr = new Object[5]; // each element of object will be an array of integers.
    for(int i = 0; i < 5; i++){
        int[][] a = new int[2*(i+1)][2*(i+1)];
        arr[i] = a;
    }
    arr[0][0][0] = 0; //error here
}

}

Answer 1

arr is Object[] so arr[0] will return an Object

But since you know that arr contains int[][] as instance of Object you will have to cast them to be so.

( ( int[][] ) arr[0] )[0][0] = 0;