Assigning two arrays equal to each other problems

Question

public static void main(String[]args) {


    int[] x = {1, 2, 3, 4};
    int[] y ;
    y = x;
    x[1] = 11;
    x = new int[2];

    x[0]=99;
    for (int i = 0; i < y.length; i++)
      System.out.print(y[i] + " ");
    System.out.println("");
    for (int i = 0; i < x.length; i++)
          System.out.print(x[i] + " ");
}

answer is

1 11 3 4 
99 0

My question is I thought when you assign two arrays, they share the same changes since they are objects... like when I set x[1] = 11; it changed the value of y, so shouldn't y still be identical to x after changing it to a 2-sized array, or since I am changing the size they no longer point to the same address?

Answer 1

int[] x = {1, 2, 3, 4};

{1, 2, 3, 4} is allocated as an array. A reference to it is assigned to x.

int[] y ;
y = x;

A reference to that same array is assigned to y as well.

x[1] = 11;

The array that both x and y refer to is now {1, 11, 3, 4}.

x = new int[2];

A new array is allocated, due to Java semantics, as {0, 0}. A reference to it is assigned to x. Now x and y refer to two different arrays. There is no resizing being done.

x[0]=99;

The array referred to by x is changed, and now contains {99, 0}. This has nothing to do with the array y refers to, which is still happily {1, 11, 3, 4}.

Answer 2

x = new int[2];

This line creates a new array with a length of 2, and then makes x point to that new array. At this point, the original array is only referenced by y.

x[0] = 99;

This line assigns the 0th element in that new array to 99, and therefore the original array is left unchanged.