Redefining a static method in subclass

[Ravinder Singh]

Friends,

Have a look at the following code:

class SuperTest{
static void a() { System.out.println("From SuperTest"); }
void printa() { a(); }
}
 
class SubTest extends SuperTest {
static void a() { System.out.println("From SubTest"); }
public static void main(String args[]){
new SubTest().printa();
}
}

Compiling and running this code prints: From SuperTest

Q. Can someone please explain why it prints "From SuperTest" and not "From SubTest" since the inherited instance method printa() is invoked on subclass reference type which I think should be considered for invoking the "redefined / redeclared" static method defined in the subclass??

---------
Ravinder

[Deepak Bala]

Think of it like this... the printa() method is being run from SuperTest and thereby calls the super method. Override this method in the sub class and the result will be different.

[Ravinder Singh]

Thanks John...

[Terry Huang]

hey John could you elaborate on that? I didn't quite understand you..

thx

[Deepak Bala]

Once you over ride the method printa() , the method a() in the sub class will get called from the subclass version of printa() . Else the method in the super class is called. So when the method is over ridden it prints "From SubTest".

[Terry Huang]

Sorry, I meant to ask if you could elaborate on why it prints "From SuperTest" not "From SubTest". Can anyone tell me why?

[marc weber]

You might be interested in this: Overriding vs. Hiding.

[wise owen]

In SuperTest class, compiler will hader code "void printa() { a(); }" to "void printa() { SuperTest.a(); }"
See Ernest's post in this thread.
[ May 21, 2006: Message edited by: wise owen ]

[Ravinder Singh]

Thanks Wise...that thread has the real explanation.

So..the compiler sees the above code as:

class SuperTest{
static void a() { System.out.println("From SuperTest"); }
void printa() { [B]SuperTest.a();[/B] }
}
 
class SubTest extends SuperTest {
static void a() { System.out.println("From SubTest"); }
public static void main(String args[]){
new SubTest().printa();
}
}

and therefore invokes the static method from super class as decided and hardcoded by the compiler at compile-time into the class file.

----------
Ravinder

[Sreeraj Harilal]

static methods can't be overridden.