Multiple inheritance of a class?

Question

I am new to Java and I have one of the typical problem.I came to know that Java do not support multiple inheritence. So I want to know how to implement the below class

class JPT extends JPanel extends Thread;

Multilevel inhertence will not help me for obvious reasons that I cannot edit the library classed, I may end up in problem due to dependencies if I edit.

+1. First time I'm seeing this question on SO. And best answer you got. +1 for answers too. — Suresh Atta, Sep 27 '13 at 06:43
In 14 years I think I've only ever really want multiple inheritance twice, end up using a proxy pattern — MadProgrammer, Sep 27 '13 at 06:47

score 4 · Answer 1 · answered Sep 27 '13 at 06:41

4

You should use the Runnable interface....

class JPT extends JPanel implements Runnable

This way you would simply create a new Thread instance, passing it a reference of you JPT class and start it...

JTP jpt = new JPT();
Thread thread = new Thread(jpt);
thread.start();

Now, I have to tell you, that just scares me.

Swing is a single threaded framework. That is, all interactions and modifications to the UI are expected to be executed from within the context of the Event Dispatching Thread, meaning you should never try and modify any UI component from any thread other than the EDT.

Take a look at Concurrency in Swing for more details

answered Sep 27 '13 at 06:41

MadProgrammer

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First I thought impossible. My silly brain :-/ – Suresh Atta Sep 27 '13 at 06:44
+1 not for making it *work* but for adding the explanation about *Swing is a single threaded framework.* – Luiggi Mendoza Sep 27 '13 at 06:44
@sᴜʀᴇsʜᴀᴛᴛᴀ Nothings impossible, doesn't make it a good idea though :P – MadProgrammer Sep 27 '13 at 06:46
@MadProgrammer He he. Good one. Just realized :P – Suresh Atta Sep 27 '13 at 06:47

score 1 · Accepted Answer · answered Sep 27 '13 at 06:42

1

If you want to create a Thread on a sub-class of Panel, you can do

class JPT extends JPanel implements Runnable
{
    JPT()
    {
        new Thread(this).start();
    }

    public void run()
    {
        // Code to run in new thread here.
    }
}

Hope this helps.

answered Sep 27 '13 at 06:42

Sri Harsha Chilakapati

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First I thought impossible. My silly brain :-/ – Suresh Atta Sep 27 '13 at 06:45
Thank you :):) now it is working fine... and thanks to others as well for your valuable comments – user2819669 Sep 27 '13 at 07:08

blackpanther · Answer 3 · 2013-09-27T06:46:28.170

1

Of course, Java does not support multiple inheritance, but you can implement multiple interfaces within a class. In your case, I would use:

class JPT extends Jpanel implements Runnable {

Anything that implements Runnable, can then be passed as an argument to the Thread constructor. E.g.

JPT JPT = new JPT();
Thread t = new Thread(JPT);
T.start();

edited Sep 27 '13 at 06:46

answered Sep 27 '13 at 06:44

blackpanther

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Multiple inheritance of a class?

3 Answers3