Why is this generics array creation not working as expected?

Question

I have the following code where I'm creating an array and trying to store objects in it. At run time, I get an ArrayStoreException.

import java.lang.reflect.Array;

public class GenericsArrayCreation<T> {

    public static <T> void Test(T[] A){
        @SuppressWarnings("unchecked")
        T[] temp = (T[]) Array.newInstance(A.getClass(), A.length);
        for(int i = 0;i<temp.length;i++){
            temp[i] = A[i];
            System.out.println(temp[i].toString());
        }
    }

    public static void main(String[] args){
        String[] strs = {"a", "b", "c"};
        GenericsArrayCreation.Test(strs);
    }
}

I somehow understand that this is because of the statement

T[] temp = (T[]) Array.newInstance(A.getClass(), A.length);

Why is this wrong? A.getClass() at runtime returns a String, so temp should be an array of strings. In that case, why is the assignment temp[i] = A[i] not working?

Answer 1

The type of A is java.lang.String[], rather than java.lang.String.

You want the component type of the array, rather than the array type itself.

Use this line instead:

T[] temp = (T[]) Array.newInstance(A.getClass().getComponentType(), A.length);

and the code runs fine.