anonymous-class

I think I understand the basics of Anonymous classes but I'd like to clarify something. when I have a syntax such as this class A { class AnonymousClass1 Implements ActionListener{} } class A { public A() { JButton btn = new JButton(); btn.addActionListener( new ActionListener(){} ); } } If the anonymous class is actually an inner class of class A, as in the first example: in theory, is the semantics right? What happens exactly? I think when the java file is compiled, a .class file is created for the anonymous class so it can be referenced (but I couldn't find it). When an object of A is

I have an example class defined like below: public class FooBar { void method1(Foo foo){ // Should be overwritten ... } } Later, when I try this: FooBar fooBar = new FooBar(){ public String name = null; @Override void method1(Foo foo){ ... } }; fooBar.name = "Test"; I get an error saying that the name field does not exist. Why? Because the type of the variable "fooBar" is FooBar (the run-time type of the object in said variable is that of the anonymous class implementing FooBar which is also a subtype of FooBar )... ...and the type FooBar does not have said member. Hence, a compile error.

This question already has an answer here: Can anonymous class implement interface? 8 answers Is there a construct in C# which allows you to create a anonymous class implementing an interface, just like in Java? As has already been stated, no, this is not possible. However, you can make a class that implements the desired interface and accepts a lambda in it's constructor so that you can turn a lambda into a class that implements the interface. Example: public class LambdaComparer<T> : IEqualityComparer<T> { private readonly Func<T, T, bool> _lambdaComparer; private readonly Func<T, int>

I was recently doing a programming assignment that required us to implement in code a program specified by a UML diagram. At one point, the diagram specified that I had to create an anonymous JButton that displayed a count (starting at one) and decremented each time it was clicked. The JButton and its ActionListener both had to be anonymous. I came up with the following solution: public static void main(String[] args) { JFrame f = new JFrame("frame"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setSize(400, 400); f.getContentPane().add(new JButton() { public int counter; { this.counter

I'm trying to make instances of anonymous classes using reflection. But ocassionally I've seen strange behaviour during instantination. Please, look at these similar fragments of code public class HideAndSeek { @SuppressWarnings("unchecked") public static void main(String[] args) throws IllegalAccessException, InstantiationException{ final String finalString = "I'm final :)"; Object object2 = new Object(){ { System.out.println("Instance initializing block"); System.out.println(finalString); } private void hiddenMethod() { System.out.println("Use reflection to find me :)"); } }; Object tmp =

Where can i use and should i use anonymous classes that are presented in PHP 7 ? I can't find a use case for them. $message = (new class() implements Message { public function getText() { return "Message"; }}); You can find the information you are looking for here , where the RFC is presented. The key points of the section Use cases are the following: Mocking tests becomes easy as pie. Create on-the-fly implementations for interfaces, avoiding using complex mocking APIs. Keep usage of these classes outside the scope they are defined in Avoid hitting the autoloader for trivial implementations