overriding methods while calling constructor

Question

I saw these codes.

I've never seen such constructor, but I guess that it creates a new A instance with the implementation of a abstract method.

what is it called?

new A() {
    @Override
    public void onEvent() {
        dosomething();
    }
};

Answer 1

are you referring to an anonymous class ? Its when you provide an implementation but never define a named class. In other words, you are providing an object in-place; you cannot reuse that definition elsewhere because you never wrote class MyClass {} , which is why it's "anonymous".

See this.

Answer 2

这是一个类型A的Object，它覆盖了A类的onEvent方法。这称为匿名类，它覆盖了一个方法