Question

Consider the following code

class A {
    static class B{
        int a = 0;
    }
    public static void main(String argc[]) {
        B var1 = new B();
        B var2 = new B();
        var1.a = 5;
        var2.a = 6;
        System.out.println(var1.a+" and "+var2.a);
    }
}

It outputs 5 and 6.
Static members are loaded only once.But the output contradicts with that statement.So surely the concept of static classes is different from static data members.So what does static mean in case of static classes

Answer 1

A copy paste from oracle:

Static Nested Classes

As with class methods and variables, a static nested class is associated with its outer class. And like static class methods, a static nested class cannot refer directly to instance variables or methods defined in its enclosing class — it can use them only through an object reference.

Note: A static nested class interacts with the instance members of its outer class (and other classes) just like any other top-level class. In effect, a static nested class is behaviorally a top-level class that has been nested in another top-level class for packaging convenience.
Static nested classes are accessed using the enclosing class name:

OuterClass.StaticNestedClass

For example, to create an object for the static nested class, use this syntax:

OuterClass.StaticNestedClass nestedObject =
     new OuterClass.StaticNestedClass();

An example:

There is no need for LinkedList.Entry or Map.Entry to be top-level class as it is only used by LinkedList aka Map. And since they do not need access to the outer class members, it makes sense for it to be static – it’s a much cleaner approach.