ActionListener gets an error it says(Finals is not abstract and does not override abstract method)

Question

Here is my code.

import java.awt.*;
import java.awt.event.*;

public class Finals extends Frame implements  WindowListener,ActionListener{
public TextField tf1;
public Button btn0,btn1,btn2,btn3,btn4,btn5,btn6,btn7,btn8,btn9,btnadd,btnminus,btndivide,btnmultiply,btnequals,btnbackspace;

public Finals(){

    Panel outputpanel = new Panel(new FlowLayout());
     tf1 = new TextField(" ",30);
     outputpanel.add(tf1);

    Panel btnpanel = new Panel(new GridLayout (5,5));

     btn0 = new Button ("0");
     btn1 = new Button ("1");
     btn2 = new Button ("2");
     btn3 = new Button ("3");
     btn4 = new Button ("4");
     btn5 = new Button ("5");
     btn6 = new Button ("6");
     btn7 = new Button ("7");
     btn8 = new Button ("8");
     btn9 = new Button ("9");

     btnadd= new Button("+");
     btnminus = new Button("-");
     btndivide = new Button ("/");
     btnmultiply = new Button ("*");
     btnequals = new Button ("=");
     btnbackspace= new Button("<-");

    btnpanel.add(btnadd);
    btnpanel.add(btnminus);
    btnpanel.add(btndivide);
    btnpanel.add(btnmultiply);
    btnpanel.add(btnequals);
    btnpanel.add(btnbackspace);

    btnpanel.add(btn1);
    btnpanel.add(btn2);
    btnpanel.add(btn3);
    btnpanel.add(btn4);
    btnpanel.add(btn5);
    btnpanel.add(btn6);
    btnpanel.add(btn7);
    btnpanel.add(btn8);
    btnpanel.add(btn9);
    btnpanel.add(btn0);

    setLayout(new BorderLayout());
    add(outputpanel,BorderLayout.NORTH);
    add(btnpanel,BorderLayout.SOUTH);
    setVisible (true);
    setSize (300,200);
    setTitle("Calculator");
    setLocationRelativeTo(null);
    setResizable(false);
    addWindowListener(this);
}

public static void mainr(String[]args){
        Finals awt = new Finals();    
}

    public void windowClosing(WindowEvent we){
            System.exit(0);
        }
     public void windowClosed(WindowEvent we){};
     public void windowOpened(WindowEvent we){};
     public void windowIconified(WindowEvent we){};
     public void windowDeiconified(WindowEvent we){};
     public void windowActivated(WindowEvent we){};
     public void windowDeactivated(WindowEvent we){};
}

what is `mainr`? please copy and past your code.. don't type.. — Abhishek Nayak, Mar 10 '14 at 05:39
Why AWT rather than Swing? See my answer on [Swing extras over AWT](http://stackoverflow.com/a/6255978/418556) for many good reasons to abandon using AWT components. — Andrew Thompson, Mar 11 '14 at 11:05

score 1 · Answer 1 · answered Mar 10 '14 at 05:42

1

You have implemented interface ActionListener so need to override actionPerformed method from that interface otherwise declare your class as abstract.

    @Override
    public void actionPerformed(ActionEvent e) {
       //your code goes here
    }

answered Mar 10 '14 at 05:42

eatSleepCode

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score 1 · Answer 2 · edited May 23 '17 at 12:13

If you're going to implements an interface (ActionListener), Then you need to @Override all of it's methods. In this case you need to implement the actionPerfomed method for your Finals class

@Override
public void actionPerformed(ActionEvent e) {
    // do something
}

Also, what is public static void mainr(String[]args){? mainr should be main
Also, make use of the @Override anotation, so you know you have successfully overridden a method, i.e.
```
@Override
public void windowClossing(WindowEvent e) {}
```
Also, Swing apps should be run on the Event Dispatch Thread (EDT). You can do so by wrapping the inside of your main method with SwingUtilities.invokeLater.... See more at Initial Threads
Also, you should setVisible(true) after setSize and setLocationXxx
Also, you should just pack() your frame, instead of setSize() so that all the components are sure to be visibly contained.
Also read up on Extends JFrame vs. creating it inside the the program
Also, why AWT and not Swing? Look into using Swing. See more at Creating GUI with Swing

OPs uses AWT Frame/Panel etc :-) – mKorbel Mar 10 '14 at 07:24 — mKorbel, Mar 10 '14 at 07:24

ActionListener gets an error it says(Finals is not abstract and does not override abstract method)

2 Answers2