doubt in Inner class...?

[Ganeshkumar cheekati]

source: www.danchisholm.net

class A {
  private static int counter;
  public static int getCounter(){return counter++;}
  private static int innerCounter;
  public static int getInnerCounter(){return innerCounter++;}
  private String name;
  A() {name = "A" + getCounter();}
  class B {
    private String name;
    B() {
      name = "B" + getInnerCounter();
      System.out.print(A.this.name + name); // 1
  }}
  void m1() {new A().new B();}  // 2
 [B]void m2() {this.new B();}     // 3[/B]
  void m3() {new B();}          // 4
  public static void main(String[] args) {
    A a1 = new A();
    a1.m1(); a1.m2(); a1.m3();
}}

answer is: Prints: A1B0A0B1A0B2

can you explain what is happening at line-3?
[ December 11, 2008: Message edited by: Ganeshkumar cheekati ]

[Ankit Garg]

ganesh you have asked about line 2 and you have made line 3 bold?? Anyways I will answer about line 2. As you might know, you need an instance of the outer class to create an instance of non-static inner class. So you are creating an instance of the inner class B, using a new object of the enclosing class i.e. A. If you are not familiar with the object.new syntax, then you must read about it a bit. You can refer to my blog too whose link is in my signature...

[Ganeshkumar cheekati]

sorry ankit...

i am asking about line-3 in the above code...

yeah i posted another one which is different than this code...
[ December 11, 2008: Message edited by: Ganeshkumar cheekati ]

[Ankit Garg]

Sorry ganesh! I didn't see the other post with caution. It is indeed different.

You have to use an outer class instance to create an instance of the inner class. Every non-static method has a instance of the associated class which can be accessed using the this keyword. Since the class B is inside the class A, and this in method m2 refers to an instance of class A, so you can use the this to create an instance of class B. Let me change the code a bit

void m2() {
   A obj = this;
   obj.new B();
}

Now it would be clearer to you. Also the method m3 also uses this to create an instance of the inner class. The method m3 is equivalent to this code

 void m3() { this.new B();}