// Parameter passing in Java: call-by-value only * 2003-03-12
//
// Compile with:
//   javac Parameters.java
// Run with: 
//   java Parameters 11 22

class Parameters {
  public static void main(String[] args) {
    int a = Integer.parseInt(args[0]);
    int b = Integer.parseInt(args[1]);
    // After the call to swapV, variables a and b are unchanged 
    System.out.println("a = " + a + "  b = " + b);
    swapV(a, b);
    System.out.println("a = " + a + "  b = " + b);
    System.out.println("----------------------------------------");
    C aa = new C(a);
    C bb = new C(b);
    // After the call to swapV, variables aa and bb are unchanged, 
    // but the f fields in the objects referred to have been changed
    System.out.println("aa = " + aa + "  bb = " + bb);
    System.out.println("aa.f = " + aa.f + "  bb.f = " + bb.f);
    swapF(aa, bb);
    System.out.println("aa = " + aa + "  bb = " + bb);
    System.out.println("aa.f = " + aa.f + "  bb.f = " + bb.f);
  }

  static void swapV(int x, int y) {
    int tmp = x; x = y; y = tmp;
  }

  static void swapF(C x, C y) {
    int tmp = x.f; x.f = y.f; y.f = tmp;
  }
}

class C {
  public int f;

  public C(int f) {
    this.f = f;
  }
}