I observed that Outer classes can access inner classes private instance variables. How is this possible? Here is a sample code demonstrating the same: class ABC{ class XYZ{ private int x=10; } public static void main(String… args){ ABC.XYZ xx = new ABC().new XYZ(); System.out.println(“Hello :: “+xx.x); ///Why is this allowed?? } } Why is this … Read more
Can someone please point me towards some nice resources for understanding and using nested classes? I have some material like Programming Principles and things like this IBM Knowledge Center – Nested Classes But I’m still having trouble understanding their purpose. Could someone please help me? 6 Answers 6
This question already has answers here: Why/when should you use nested classes in .net? Or shouldn’t you? (14 answers) Closed 9 years ago. I’m trying to understand about nested classes in C#. I understand that a nested class is a class that is defined within another class, what I don’t get is why I would … Read more
I have the following code. I want to get hold of the outer class object using which I created the inner class object inner. How can I do it? public class OuterClass { public class InnerClass { private String name = “Peakit”; } public static void main(String[] args) { OuterClass outer = new OuterClass(); InnerClass … Read more
I have been reading some articles on memory leaks in Android and watched this interesting video from Google I/O on the subject. Still, I don’t fully understand the concept, and especially when it is safe or dangerous to user inner classes inside an Activity. This is what I understood: A memory leak will occur if … Read more
I have the following code: class Hello { class Thing { public int size; Thing() { size = 0; } } public static void main(String[] args) { Thing thing1 = new Thing(); System.out.println(“Hello, World!”); } } I know Thing does nothing, but my Hello, World program compiles just fine without it. It’s only my defined … Read more
This question already has answers here: Java inner class and static nested class (28 answers) Closed 8 years ago. What is the difference between static and non-static nested class? 8 Answers 8
I’m playing with lambdas in Java 8 and I came across warning local variables referenced from a lambda expression must be final or effectively final. I know that when I use variables inside anonymous class they must be final in outer class, but still – what is the difference between final and effectively final? 14 … Read more
I’m trying to make a Tetris game and I’m getting the compiler error Shape is not an enclosing class when I try to create an object public class Test { public static void main(String[] args) { Shape s = new Shapes.ZShape(); } } I’m using inner classes for each shape. Here’s part of my code … Read more
What is the main difference between an inner class and a static nested class in Java? Does design / implementation play a role in choosing one of these? 2 28 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 … Read more
