Modify an array passed as a method-parameter

Question

Suppose I have an int-array and I want to modify it. I know that I cannot assign a new array to array passed as parameter:

public static void main(String[] a         


        

Answer 1

As you correctly note, you cannot assign to the array reference passed as a parameter. (Or more precisely, the assignment won't have any effect in the caller.)

This is about the best that you can do:

public static void method(int[] n) {
    int[] temp = new int[]{2};
    for (int i = 0; i < temp.length; i++) {
        n[i] = temp[i];
    }
    // ... or the equivalent using System.arraycopy(...) or some such
}

Of course, this only works properly if the size of the input array is the same as the size of the array you are copying to it. (How you should deal with this will be application specific ...)

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For the record Java passes the array reference by value. It doesn't pass the array contents by value. And clone won't help to solve this problem. (At least, not with the method signature as declared.)