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'[Class] is not abstract..' error when i use 'implements'

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Join Date: Oct 2004

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javaLearner javaLearner is offline

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Newbie Poster

'[Class] is not abstract..' error when i use 'implements'

Oct 5th, 2004

G'day..

Am new to this whole object oriented stuff. But keen to learn. Am trying to compile this class but keep getting the following error when i declare anything that 'implements'. i remove the declarations and all subsequent code references and she compiles.. any ideas??

*********************START_OF_ERROR**********************
ChatClientApplication.java:6: ChatClientApplication is not abstract and does not override abstract method actionPerformed(java.awt.event.ActionEvent) in java.awt.event.ActionListener public class ChatClientApplication extends Frame implements ActionListener, Item
Listener, WindowListener
^
1 error
***********************END_OF_ERROR**********************
Cheers..
:eek:

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Join Date: Aug 2004

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cosi

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Re: '[Class] is not abstract..' error when i use 'implements'

Oct 6th, 2004

To implement an interface (in this case ActionListener or ItemListener), you must write all the functions that the interface provides. One such function you're missing is actionPerformed(ActionEvent). If you put this function into your ChatClientApplication class, it will stop complaining.

Put this in your class:

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
 public void actionPerformed(java.awt.event.ActionEvent e)
 {
 }
 public void actionPerformed(java.awt.event.ActionEvent e)
 {
 }

Hope this helps!

Ed

•

Originally Posted by javaLearner

*********************START_OF_ERROR**********************
ChatClientApplication.java:6: ChatClientApplication is not abstract and does not override abstract method actionPerformed(java.awt.event.ActionEvent) in java.awt.event.ActionListener public class ChatClientApplication extends Frame implements ActionListener, Item
Listener, WindowListener
^
1 error
***********************END_OF_ERROR**********************
Cheers..
:eek:

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Join Date: Oct 2004

Posts: 5

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Re: '[Class] is not abstract..' error when i use 'implements'

Oct 7th, 2004

Hi Ed,

that's brilliant! Thankyou, code compiles now..

-> ha! So now of course I attempt to run it and get:
----------------------------------------------------------------------
C:\Java Chat Application WIP\My Source>java ChatClientApplication.class
Exception in thread "main" java.lang.NoClassDefFoundError: ChatClientApplication
/class
----------------------------------------------------------------------
I am not 'constructing' correctly??, i.e.

public class ChatClientApplication extends Frame implements ActionListener, ItemListener, WindowListener

and then:

//Class constructor method..
public ChatClientApplication()
{
// initialise the user interface
init();
}

and then:

//Main method to bring everything together..
public static void main(String args[])
{
new ChatClientApplication();
}

...if anyone is bored and wants to help!
:eek:

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Join Date: Aug 2004

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Junior Poster

Re: '[Class] is not abstract..' error when i use 'implements'

Oct 8th, 2004

Don't have the .class at the end.

Just run the line
java ChatClientApplication

Hope this helps. ;-)

Ed

•

Originally Posted by javaLearner

Hi Ed,

that's brilliant! Thankyou, code compiles now..

-> ha! So now of course I attempt to run it and get:
----------------------------------------------------------------------
C:\Java Chat Application WIP\My Source>java ChatClientApplication.class
Exception in thread "main" java.lang.NoClassDefFoundError: ChatClientApplication
/class
----------------------------------------------------------------------

•

In a world without walls or fences,
What use are Windows and Gates.

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Join Date: Oct 2004

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Re: '[Class] is not abstract..' error when i use 'implements'

Oct 10th, 2004

Good point, thankyou Ed.

Turns out I did not have my CLASSPATH environment variable set correctly (set CLASSPATH=), so class files could not be found and nothing was able to run..

Thanks for help anyway..

:-|