Help required on java.lang.StackOverFlowError and static initializer

Question

I wanted to create an instance of a class that contains another instance of the same class. So I wrote:
class A {
     A z = new A ();     
     void display () {
          System.out.println ("Hello World");
     public static void main (String [] args) {
          A y = new A();
          y.display ();
}During execution I got java.lang.StackOverFlowError. But if I put a static initializer, it works fine. Here is the code using static initializer.
class A {
     static{
          A z = new A ();     
     void display () {
          System.out.println ("Hello World");
     public static void main (String [] args) {
          A y = new A();
          y.display ();
}Could anyone please help me to understand the logic why "java.lang.StackOverFlowError" is happening here and how the same program runs fine by putting a static initializer ?
Regards,
Shambhu

Answer 1

Could anyone please help me to understand the logic
why "java.lang.StackOverFlowError" is happening hereWhen you instantiate an A object with A y = new A () then A z = new A () also gets executed inside the A class, which in it's turn executes A z = new A () again, and again, and again...
and how the same program runs fine by putting a
static initializer ?Because the static block gets executed only once.
The use of class- and instance variables is explained in more detail here:
http://java.sun.com/docs/books/tutorial/java/javaOO/classvars.html