Enthuware question doubt

[Hareendra Reddy]

I got the question from here(Qno: 14)..

class A
{
}
public class TestClass
{
	public class A
	{
		public void m() { }
	}
	class B extends A
	{
	}
	public static void main(String args[])
	{
		new TestClass().new A() { 	 public void m() { } };
	}
}

(a) This program will not compile.
(b) class created inside the main method is static.
(c) class created inside the main method is final.
(d) Objects of class B cannot be created inside the main method just by doing "new B()"
(e) None of these.

The answers are given as c and d ...
I believe only d is correct and how can we can know about the nature of anonymous class??

Thanks

[Ikpefua Jacob-Obinyan]

Hareendra Reddy wrote:I got the question from here(Qno: 14)..

class A
{
}
public class TestClass
{
	public class A
	{
		public void m() { }
	}
	class B extends A
	{
	}
	public static void main(String args[])
	{
		new TestClass().new A() { 	 public void m() { } };
	}
}

(a) This program will not compile.
(b) class created inside the main method is static.
(c) class created inside the main method is final.
(d) Objects of class B cannot be created inside the main method just by doing "new B()"
(e) None of these.

The answers are given as c and d ...
I believe only d is correct and how can we can know about the nature of anonymous class??

Thanks

Dear friend..... c AND d are correct! A class created INSIDE a method (including static methods) is called METHOD-LOCAL-INNER-CLASS.
The same rules apply to LOCAL VARIABLE DECLARATIONS.
The ONLY modifiers you can use are either abstract OR final. NEVER both at the same time!!.
So c is correct! as well as d.

Try this:

public class TestFinal{
    public static void main(String[] args){
    // declaration of method-local-inner-classes
        final class A{ }
        abstract class A2{ }
    // final abstract class A3{ } WILL NOT COMPILE!!
}
}

Remember that I am studying java just like you AND others, DO NOT rely on me 100%, I am NOT above mistakes. Thank you for your understanding.

Hey! After reading CAREFULLY the options I agree with you that option c is wrong!.
Here is my understanding:
1. class created inside the main method "IS" final.
2. class created inside the main method "CAN BE" final. // this sounds better.

[Hareendra Reddy]

Thank you Ikpefua Jacob-Obinyan ...

Yeah you are saying right, anonymous inner classes are similar to method lcoal inner classes...
But we didn't mark the class final (any way we can't) , then how can we say that it is final ??

[Ikpefua Jacob-Obinyan]

Hareendra Reddy wrote:Thank you Ikpefua Jacob-Obinyan ...

Yeah you are saying right, anonymous inner classes are similar to method lcoal inner classes...
But we didn't mark the class final (any way we can't) , then how can we say that it is final ??

It is NOT final and at the moment I have NOT seen such a syntax, I seriously doubt if it exists.

Let us analyse line 15 of your code READ CAREFULLY:

 
new TestClass().new A() {    public void m() { } };   // line 15 of your code

new TestClass().new A()                                      // Instantiation of a SUBCLASS of INNER-CLASS A { }
                                                                      

{                                                                     //  Declaration of ANONYMOUS-INNER-CLASS

     public void m() {                                            //  Overriding class A's public void m() method !! 

          }
   };                                                                 //  End of ANONYMOUS-INNER-CLASS 

Observation:
Did you take note of the semi-colon that ends the curly braces in line 11 ??
That is how to know an anonymous inner class.
The semi colon ought to have ended the instance declaration in line 4!! but it did not!!
That is how you identify anonymous inner classes.
The SOLE purpose of anonymous inner class is to override methods.
I am sorry I dont have more details, you will have to investigate that yourself. Thanks.

[Paul Anilprem]

Hello,
The given answer is correct.
From Java Language Specification:

15.9.5 Anonymous Class Declarations
An anonymous class declaration is automatically derived from a class instance creation expression by the compiler.
An anonymous class is never abstract (§8.1.1.1). An anonymous class is always an inner class (§8.1.3); it is never static (§8.1.1, §8.5.2). An anonymous class is always implicitly final (§8.1.1.2).

HTH,
Paul.

[Ikpefua Jacob-Obinyan]

Paul Anilprem wrote:Hello,
The given answer is correct.
From Java Language Specification:

15.9.5 Anonymous Class Declarations
An anonymous class declaration is automatically derived from a class instance creation expression by the compiler.
An anonymous class is never abstract (§8.1.1.1). An anonymous class is always an inner class (§8.1.3); it is never static (§8.1.1, §8.5.2). An anonymous class is always implicitly final (§8.1.1.2).

HTH,
Paul.

Thanks Paul...I was NOT sure about the issue of final in an anonimous classes and this information is FUNDAMENTAL to learners like us.
Once again thanks for your intervention.

[Hareendra Reddy]

Thank you Paul Aniprem...