Inner classes, also called Nested Classes, are nothing but classes that are defined within other classes. The nesting is a relationship between classes, not objects.
Inner classes have clearly two benefits, name control & access control. In Java, this benefit is not as important because Java packages give the name control.
Java inner classes have feature that makes them richer and more useful. An object of an inner class has an implicit reference to the outer class object that instantiated it. Through this pointer, it gains access to any variable of the outer object. Only static inner classes don’t have this pointer. It is actually invisible when we write the code, but compiler takes care of it. Inner classes are actually a phenomenon of the compiler and not the JVM.
