Object References as Parameters

Object References as Parameters

Object references can be parameters. Call by value is used, but now the value is an object reference. This reference can be used to access the object and possibly change it. Here is an example program:

class ObjectPrinter
{
  public void print( String st )
  {
    System.out.println("Value of parameter: " + st );    
  }
}

class OPTester
{
  public static void main ( String[] args )
  {
    String message = "Only One Object" ;

    ObjectPrinter op = new ObjectPrinter();

    System.out.println("First  value of message: " + message );    
    op.print( message );
    System.out.println("Second value of message: " + message );    
  }
}

In this program, the local variable message contains a reference to a String object. A copy of that reference is made in the formal parameter st of the print() method. The object is not copied.