How do I make a copy of an Array, which I can return in a public method?

Question

Basically I got told that I shouldn't have public methods returning Arrays for "future" security purposes. Instead they should be private, and if I wanna return an Array it would have to be some kind of copy in another method.

This is how it looks now..

public Object[] ownedObject() {

    return objectArr;
}

If I make this private the class that needs it doesn't recognize the method above.

Thing is I need to use the contents in that Array in said, other class, and the total project, as I have it right now with 5 different classes, works (with the returning Array-methods set to Public and not private).

Answer 1

As you are concerned with security aspect of this problem you might want to distinguish between shallow copy and deep copy of the array . If your array contains mutable objects you probably need a deep copy of every single element in the array to ensure that state is not leaking from your object.

Assuming that you array is of type MyType with a copy constructor :

public MyType[] ownedObject() {
    MyType[] copyArr = new MyType[objectArr.lenght];
    for (int i = 0; i < objectArr.lenght; i++) {
        copyArr[i] = new MyType(objectArr[i]);
    }
    return copyArr;
}

There are also other ways to deep copy an object .