private method resolution

[anjali desh]

Hi all,
Maybe my doubt is repetitive but am genuinely stumped.
See the following code

  
class R {
  private void printS1(){System.out.print("R.printS1 ");}
  protected void printS2() {System.out.print("R.printS2 ");}
  protected void printS1S2(){printS1();printS2();}
}
class S extends R {
  private void printS1(){System.out.print("S.printS1 ");}
  protected void printS2(){System.out.print("S.printS2 ");}
  public static void main(String[] args) {
 S s = new S();
  s.printS1S2();
}}

Now according to me the output should be S.printsS1 S.printsS2..but actually it turns out to be R.printsS1 S.printsS2. Now my doubt is that the call to a private method is resolved at compile time depending on the type of reference.The type of reference is s.So shouldnt the private method in S be called which hides the one in R?
[ October 06, 2005: Message edited by: Barry Gaunt ]

[jaman tai]

Hi. In my opinion, I don't think there is no override relationship between 2 printS1() mothods because they are private.

[jaman tai]

Oh, I am sorry. Typing mistake. I mean there is no relationship between the private methods.

[Jon Lee]

private and static methods (also class instance member, no matter what access modifier it has) are "early binding" at compile time. Other methods are "late binding" and calls to these methods are resolved at run time, which enables the so called "Polymorphism".

In your code, R.printS1()is a private method, so it is binded at compile time. R.printS2() is protected, so "Polymorphism" is applicable.

When you invoke s.printS1S2(), R.printS1S2() is invoked. It then invoke printS1()which is binded to R.printS1() at compile time, and invoke S.printS2() due to Polymorphism.

That's it. Hope it helps, mate.

[anjali desh]

But s.printS1S2() means the inherited printS1S2() is called .and then since the type of reference is s ,the private method of S should be called.
Dont know why this is confusing me!!!

[Lalitha Gottumukkula]

Check this....

 class R {
private void printS1() {    //............................. ( 1 )
System.out.print("R.printS1 ");
} 
protected void printS2() {  //............................. ( 2 )
System.out.print("R.printS2 ");
} 
protected void printS1S2() {
printS1(); // since private, it is binded to the function 1
   // at compile time itself. No matter upon which instance 
   // the funtion printS1S2() is being called, only the
   // function at line ( 1 ) will be called. 
 
printS2(); // since not private, binding is decided at runtime
}
}
 
class S1 extends R {
public void printS1() {
System.out.print("S1.printS1 ");
} 
protected void printS2() {
System.out.print("S1.printS2 ");
} 
}
 
class S extends R {
private void printS1() {
System.out.print("S.printS1 ");
} 
protected void printS2() {
System.out.print("S.printS2 ");
} 
public static void main(String[] args) {
S s = new S(); 
s.printS1S2();

S1 s1 = new S1(); 
s1.printS1S2();
}
} 

Hope this helps.

[anjali desh]

Thank you so much Lalitha....!!
The answer is SPOT-ON and there is absolutely no confusion left now.
I appreciate the time and effort spent by you all in clarifying my doubt so soon!!

[Ashok George]

that was truly a great reply for the doubt good work !!!
thaxn from mw too i was watching closely on the thread!!!