Question

I have implemented array list with arrays:

public class ArrayIndexList<E> {
    private E[] A;
    private int capacity = 5; // Initial Array Size
    private int size = 0;

    public ArrayIndexList() {
        A = (E[]) new Object[capacity];
    }

    public void add(int index, E element) {
        /* if array is full:
         * 1. double the array size
         * 2. copy elements to the new array */
        if (size == capacity) {
            capacity = capacity * 2;
            E[] B = (E[]) new Object[capacity];
            for (int i = 0;i < size;i++)
            B[i] = A[i];
            A = B;
        }

        // shift the elements up
        for (int i = size - 1;i >= index;i--)
            A[i + 1] = A[i];

        // add new element
        A[index] = element;
        size = size + 1;
    }

    public E remove(int index) {
        E temp = A[index];

        //shift elements down
        for (int i = index;i < size - 1;i++)
            A[i] = A[i + 1];
        size = size - 1;

        return temp;
    }
}

It is working, but compiler gives warning:

Type safety: Unchecked cast from Object[] to E[] ArrayIndexList.java

What’s wrong with the code?

Answer 1

The cast cannot be checked a runtime, therefore a warning is given. With
an up to date compiler, you can suppress the warning using @SuppressWarnings("unchecked").

was it helpful ?

http://mindprod.com/jgloss/compileerrormessages.html#TYPESAFETYERASED