Question

I have started learning Java language for Android Application developement.

As per my understanding based on static class, we cannot instantiate object of static class.

But why instantiation of static nested class object is allowed in following situaltion?

class EnclosingClass 
{     
      //...     
      class static StaticInnerClass 
      {         
          //...     
      } 
} 

Why we can create object of inner class if it is marked as static?

EnclosingClass.StaticInnerClass s = new EnclosingClass.StaticInnerClass()

Answer 1

As per my understanding based on static class, we cannot instantiate object of static class.

Your understanding of the meaning of “static class” is incorrect. Basically a “static class” in Java is a nested class which doesn’t have an implicit reference to an instance of the containing class. See section 8.5.1 of the JLS for more information, in particular:

The static keyword may modify the declaration of a member type C within the body of a non-inner class or interface T. Its effect is to declare that C is not an inner class. Just as a static method of T has no current instance of T in its body, C also has no current instance of T, nor does it have any lexically enclosing instances.

Perhaps you were thinking of static classes in C#, which are completely different?