What's this language feature called?

Question

JPanel panel = new JPanel() {
        public void setBackground(Color c) {
           Logger.global.info("setBackground: c=" + c);
           super.setBackground(c);
        }
    };

I only know I can do JPanel panel = new JPanel();

Why can someone do the above? What's the name for it?

score 7 · Accepted Answer · edited May 23 '17 at 10:34

7

It is called an anonymous class.

That code basically creates a subclass of JPanel "on the fly" without giving it a name (thus the term anonymous class) and instantiates it.

Related questions and links:

edited May 23 '17 at 10:34

Community

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answered Oct 27 '11 at 14:10

aioobe

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To be more exact anonymous inner class. – AlexR Oct 27 '11 at 14:12
3

@AlexR, an anonymous class is *always* an inner class so "anonymous inner class" is kind of redundant. – aioobe Oct 27 '11 at 14:13

score 0 · Answer 2 · answered Oct 27 '11 at 14:38

0

It is an anonymous class that you extend and define additional methods or override existing ones.

Note that the same way you can extend interfaces or abstract classes.

answered Oct 27 '11 at 14:38

mishadoff

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What's this language feature called?

2 Answers2