Question

System.arraycopy() is a shallow copy method.

For an array of a primitive type, it will copy the values from one array to another:

int[] a = new int[]{1,2};
int[] b = new int[2];
System.arraycopy(a, 0, b, 0, 2);

b will be {1,2} now. Changes in a will not affect b.

For an array of a non-primitive type, it will copy the references of the object from one array to the other:

MyObject[] a = new MyObject[] { new MyObject(1), new MyObject(2)};
MyObject[] b = new MyObject[2];
System.arraycopy(a, 0, b, 0, 2);

b will contain a reference of new MyObject(1), new MyObject(2) now. But, if there are any changes to new MyObject(1) in a, it will affect b as well.

Are the above statements correct or not?

Answer 1

Above statements are correct or not?

Yes, you are correct.

System.arraycopy always does a shallow copy, no matter if the array contains references or primitives such as ints or doubless.

Changes in array a will never affect array b (unless a == b of course).

But if any changes of new MyObject(1) in a, it will affect b as well.

Depends on what you mean. To be picky, a change to the new MyObject(1) will neither affect a nor b (since they only contain references to the object, and the reference doesn’t change). The change will be visible from both a and b though, no matter which reference you use to change the object.