An inner class, by definition, cannot be static, so I am going to recast your question as “What is the difference between static and non-static nested classes?” A non-static nested class has full access to the members of the class within which it is nested. A static nested class does not have a reference to … Read more
What you are asking is a pretty tough question. While you may think it is just one question, you are actually asking several questions at once. I’ll do my best with the knowledge that I have to cover it and, hopefully, some others will join in to cover what I may miss. Nested Classes: Introduction … Read more
what I want to know is why java forbids static fields/methods inside inner classes Because those inner classes are “instance” inner classes. That is, they are like an instance attribute of the enclosing object. Since they’re “instance” classes, it doesn’t make any sense to allow static features, for static is meant to work without an … Read more
The inner class is just a way to cleanly separate some functionality that really belongs to the original outer class. They are intended to be used when you have 2 requirements: Some piece of functionality in your outer class would be most clear if it was implemented in a separate class. Even though it’s in … Read more
… starting in Java SE 8, a local class can access local variables and parameters of the enclosing block that are final or effectively final. A variable or parameter whose value is never changed after it is initialized is effectively final. For example, suppose that the variable numberLength is not declared final, and you add … Read more
static class Thing will make your program work. As it is, you’ve got Thing as an inner class, which (by definition) is associated with a particular instance of Hello (even if it never uses or refers to it), which means it’s an error to say new Thing(); without having a particular Hello instance in scope. … Read more
From the Java Tutorial: Nested classes are divided into two categories: static and non-static. Nested classes that are declared static are simply called static nested classes. Non-static nested classes are called inner classes. Static nested classes are accessed using the enclosing class name: OuterClass.StaticNestedClass For example, to create an object for the static nested class, … Read more
So getters and setters are non-static methods (in most cases). What this means is that you will have to instantiate the object and then call the methods. So what you have to do is create Address instance Address a = new Address (…); and then you can use the instance to call your getters and … Read more