An object inside its own class

So let's say:

public class Sample {  //main() class
    public static void main(String[] args) {
      A a = new A();
    }
}

public class A {
  A aa = new A();
}

  1. So...when I run it ...it gives : java.lang.StackOverflowError. So, my explanation is that object a generation at line 1, furthers creates object aa generation at line 2...and then it enters a recursion .... which keeps creating object after object, until the heap memory is full.

  2. If the objects are created on Heap...then why does it say StackOverflowError ??

Jon Skeet
people
quotationmark

Well, it's using both heap and stack. The stack space is because you're in the constructor for A, recursively. It would be simpler to see this if you put the initialization in the body of the constructor:

public class A {
  A aa;

  public A() {
     aa = new A();
  }
}

So the A constructor calls itself, then calls itself, etc. There's generally rather more heap space available than stack space, hence why you're running out of stack space first. If your class had a lot of fields, you would conceivably run out of heap space first - although usually the heap is pretty huge in modern machines.

people

See more on this question at Stackoverflow