Changes to the Formal Parameter
do not affect the Caller

Here is the program again, with a slight change. Now the invoked method print() makes a change to its copy of the value in its formal parameter x.

class SimpleClass
{
  public void print( int x )
  {
    System.out.println("First  value of the parameter: " + x );
    x = 100;       // local change to the formal parameter 
    System.out.println("Second value of the parameter: " + x );
  }
}

class SimpleTester
{
  public static void main ( String[] args )
  {
    int var = 7;
    SimpleClass simple = new SimpleClass();

    System.out.println("First  value of the local var: " + var );    
    simple.print( var );
    System.out.println("Second value of the local var: " + var );    
  }
}

Recall that this is using call by value which means parameters are used to pass values into a method, but not used to pass anything back to the caller.