Anonymous Classes

[Pradeep Balasubramanian]

Consider the following code,

public class OuterClass {
 
public void display(){
 
System.out.println("Outer class display method");
 
}
 
class InnerClass {
 
OuterClass a = new OuterClass(){
 
public void display(){
 
System.out.println("Inner class display method");
 
}
};
 
public void display() {
 
a.display();
 
new OuterClass().display();
 
}
}
 

public static void main(String args[]) {
 
OuterClass.InnerClass obj = new OuterClass().new InnerClass();
obj.display();
 
}
 
}

When I compile the above code,
I get the following output.

Inner class display method
Outer class display method

When I make some changes in the code
and looks as below

public class OuterClass {
 
public void display(){
 
System.out.println("Outer class display method");
a.display();
}
 
//class InnerClass {
 
OuterClass a = new OuterClass(){
 
public void display(){
 
System.out.println("Inner class display method");
 
}
};
 
//public void display() {
 
//a.display();
 
//new OuterClass().display();
 
//}
//}
 

public static void main(String args[]) {
 
OuterClass obj = new OuterClass();
obj.display();
 
}
 
}

i guess i would get the same output as I got in the previous case
But, I am getting an error @ runtime (Stack Overflow Error)

Why is it so?

[Ralph Jaus]

I explained the problem there link

[ramesh maredu]

Hi,

When you are creating object of class,all instance variables will be given their default values initially,here in main method when you create object of outer class its instance variable(a) will be given its default value i.e again one more outerclass object will be created, again for this object's instance variable it will try to create outerclass object, like that it will go on and will end up with StackOverflow error.

[Pradeep Balasubramanian]

But Again I am getting StackoverflowError,
when I call by using "new OuterClass()" or "new OuterClass().display()"


I need to get an output without StackOverflowError?

:roll:
[ July 18, 2008: Message edited by: Pradeep Balasubramanian ]

[ramesh maredu]

as long as anonymous class reference a is there as instance variable you will get the same error when you say new OuterClass()
try this

 
public class OuterClass {
public void display(){
System.out.println("Outer class display method");
}
public static void main(String args[]) {
OuterClass a = new OuterClass(){
public void display(){
System.out.println("Inner class display method");
}
};
a.display();

}
}
 
 

[ July 18, 2008: Message edited by: ramesh maredu ]

[Raphael Rabadan]

Originally posted by Pradeep Balasubramanian:
But Again I am getting StackoverflowError,
when I call by using "new OuterClass()" or "new OuterClass().display()"


I need to get an output without StackOverflowError?

:roll:

[ July 18, 2008: Message edited by: Pradeep Balasubramanian ]

You are getting it when you call new OuterClass(); because each instance of OuterClass has a variable instance initialized with a new OuterClass. So it will be creating the new OuterClass() and your variables instances forever.