Curly braces in “new” expression? (e.g. “new MyClass() { … }”)

Question

What do the curly braces do there ?

handler1 = new Handler() {

        public void handleMessage() {

       }
};

object = new Class

Answer 1

Instantiates & returns reference of an anonymous subclass of current class.

new Handler() {};

Inside curly braces, definition of anonymous subclass (to be named as Handler$1 by compiler after compilation) can be specified.

It is as equal as extending the Handler class explicitly but it requires name specification obviously of subclass & so it will not remain anonymous any longer.

Following code might help to understand Instantiates & returns reference of an anonymous subclass of current class.

class Main{
    int a = 5;
    void func(){}
    void meth(){
        Main ref2 = new Main() {
            void func(){
                System.out.println(a);
            }           
        };
        ref2.func();
    }    
    public static void main(String[] args) {
        Main mm = new Main();
        mm.meth();
    }
}
//5