Question

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How are Anonymous (inner) classes used in Java?

i have a question about java. i saw this in many sources…

Class object = new Class()
{
    // What is this, a subclass or what ?
    public void someRandomMethod()
    { 
    }
};

umm if is a subclass, when i make the object the class is executed automatically ? I’m confused

and sorry about my english, i try to do my best.

Many thanks !

Answer 1

It’s called an anonymous class. Yes, the class will automatically be extended. This pattern is most commonly used to create callback interfaces such as Runnable or ActionListener.

Thread foo = new Thread(new Runnable() {
    @Override
    public void run() {
        System.out.println("Hello World");
    }
});
foo.start(); // Hello World

This creates a new instance of Runnable and passes it to the Thread for execution. This was Java’s early substitute for closures.