Override method of object like in JavaScript

Question

In JavaScript I can write:

myobject.doSomething = function() {
    // stuff..
}

So how do I use this @Override-thing of Java to achieve the same?

Can you be please more specific about your issue. And please don't ask us convert code from one language to another. We don't do it. — Rohit Jain, Jul 20 '13 at 20:48
You can't do that in Java. It's not a dynamic language like JavaScript. — JB Nizet, Jul 20 '13 at 20:51
Java's OO is not prototype-based, unlike that of Javascript. So you cannot do this. — Oliver Charlesworth, Jul 20 '13 at 20:51
`@Override` doesn't *do* anything. It's simply an *annotation*, that [allows the compiler to perform further sanity checking](http://stackoverflow.com/questions/94361/when-do-you-use-javas-override-annotation-and-why). — Oliver Charlesworth, Jul 20 '13 at 20:55
@partofweb: you're basically asking us to explain you the principle of inheritance and polymorphism in Java. Read a good book or tutorial. This is a too broad question for SO. My advice: try to forget what you know about JS when learning Java. They're completely diferent languages, with completely different approaches. — JB Nizet, Jul 20 '13 at 21:01
oh. okay. so now that I know that it is not possible in the way I need it, should I delete the question? — andy, Jul 20 '13 at 21:03

score 4 · Accepted Answer · answered Jul 20 '13 at 20:51

You cannot override a method of a single object in Java because Java is not a functional language. You can, however, override the method in a subclass of the class declaring your method.

Declaring an anonymous class:

new MyClass() {
    @Override void myMethod() {
        ....
    }
}

score 2 · Answer 2 · edited Apr 23 '18 at 13:46

Do you mean something like this?

Main.java

private class SuperClass
{
    public void myMethod()
    {
        System.out.println("Test!");
    }
}

private class ChildClass extends SuperClass
{
    @Override
    public void myMethod()
    {
        System.out.println("Testtest!");
    }
}

public class Main
{
    public static void main(String[] args)
    {
        SuperClass superInstance = new SuperClass();
        ChildClass childInstance = new ChildClass();

        superInstance.myMethod();
        childInstance.myMethod();
    }
}

score 0 · Answer 3 · answered Jul 20 '13 at 21:56

You can do this when the object is being created using an anonymous class; basically you create a subclass for the one object only. Example:

Label label = new Label() {
    @Override
    public void setText(String text) {
        super.setText(text);
        System.out.println("Text has been set to " + text);
    }
};

label.setText("Test");

Override method of object like in JavaScript

3 Answers3