Little problem with a simple function

Question

class function{
     public static int adjust (int m, int[] n){
          m++;
          n[0]++;
          return 1;          
     public static void main(String [] args){
          int m = 4;
          int[] n = {4};
          adjust(m,n);
          System.out.println(m);
          System.out.print(n[0]);
Why does it print:
4
5
and not:
5
5
Why does n[0] increase by one and not m?
Is there a simple way to fix this, so that both gets the value 5?

Answer 1

Because Java is always pass-by-value.
A copy of m is passed, 1 is added to that copy, the original m is never touched.
A copy of the reference to the array is passed, 1 is added to the 0th element of the array, the original variable (reference) n is never touched but both it and the copy reference the same array.