Regarding static classes

[Siva Sekhar]

can any one explain me the following code...


In the following case ans is "B"

11. static class A {
12. void process() throws Exception { throw new Exception(); }
13. }
14. static class B extends A {
15. void process() { System.out.println("B"); }
16. }
17. public static void main(String[] args) {
18. new B().process();
19. }

[Antonio Tercero]

I suppose A and B are static nested classes.
Class B overrides process() method : it's ok, it doesn't have to throw Exception.
From main method, there's a call to process() method on an instance of class B.
The output is "B"

[Siva Sekhar]

But when Itried to compile the code i got errors
C:\Documents and Settings\10085\Desktop\Practise>javac B1.java
B1.java:1: modifier static not allowed here
static class A1 {
^
B1.java:4: modifier static not allowed here
public static class B1 extends A1 {
^
2 errors

Here classes A is cahnged to A1 and B is B1

[Antonio Tercero]

A class can only be marked static if it's a static nested class.
Example:

    
public class TopLevelClass{
static class A {
          void process() throws Exception { throw new Exception(); }
 }
static class B extends A {
 void process() { System.out.println("B"); }
 }
 
        public static void main(String[] args){
  new B().process();
 
}
}

[Vishwanath Krishnamurthi]

Hi Siva,

Do quote your sources...

Normally you can't use the static modifier to a class..
for eg:

static class House
{
 
}

is wrong... Thats meaningless too.


but

class House
{
 
 static class AreaInfo
  {
 

  }
}

is okay.. Now AreaInfo is a class thats nested in House and its a static member of House class. That means that you can create an instance of AreaInfo even without having an instance of House.

In the question, the line no starts from 11... so we assume that theres a class in which two classes A and B are nested.. and hence the output...

Regards,
Vishwa

[Siva Sekhar]

Thanks a lot....
Now I got the point