Why can't I implement two ActionListeners on two inner classes?

Question

I'm doing the double actionlistener exercise detailed in Head First Java, and learn about inner classes, but for some reason my code is not compiling. I'm getting argument invalid errors when I try to call the addActionListener method for JButton.

TwoButtons.java:

import javax.swing.*;
import java.awt.*;

public class TwoButtons {
    JFrame frame;
    JLabel label;

    public static void main(String[] args){
        TwoButtons gui = new TwoButtons();
        gui.go();
    }

    public void go(){
        frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JButton labelButton = new JButton("Change Label");
        labelButton.addActionListener(new LabelListener());

        JButton colorButton = new JButton("Change circle");
        colorButton.addActionListener(new ColorListener());

        label = new JLabel("I'm a label");
        MyDrawPanel drawPanel = new MyDrawPanel();

        frame.getContentPane().add(BorderLayout.SOUTH, colorButton);
        frame.getContentPane().add(BorderLayout.CENTER, drawPanel);
        frame.getContentPane().add(BorderLayout.EAST, labelButton);
        frame.getContentPane().add(BorderLayout.WEST, label);

        frame.setSize(300,300);
        frame.setVisible(true);

    }

    class LabelListener implements ActionListener{
        public void actionPerformed(ActionEvent event){
            label.setText("OUch!");
        }
    }//close inner class

    class ColorListener implements ActionListener{
        public void actionPerformed(ActionEvent event){
            frame.repaint();
        }
    } //close inner class

}

MyDrawPanel.java: (no errors)

import java.awt.*;
import javax.swing.*;


public class MyDrawPanel extends JPanel{
    public void paintComponent(Graphics g){
        Graphics2D g2d = (Graphics2D) g;

        int red = (int)(Math.random()*255);
        int green = (int)(Math.random()*255);
        int blue = (int)(Math.random() * 255);
        Color startColor = new Color(red,green,blue);

        red = (int)(Math.random()*255);
        green = (int)(Math.random()*255);
        blue = (int)(Math.random() * 255);
        Color endColor = new Color(red, green, blue);

        GradientPaint gradient = new GradientPaint(70,70, startColor, 150,150, endColor);
        g2d.setPaint(gradient);
        g2d.fillOval(70, 70, 100, 100);

    }

}

Can you share the exact error please? – Mureinik Sep 19 '14 at 17:16 — Mureinik, Sep 19 '14 at 17:16

score 2 · Accepted Answer · answered Sep 19 '14 at 17:17

2

You need to import ActionEvent and ActionListener:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

They reside under java.awt.event.* and not java.awt.*.

If you use an IDE like Eclipse, you can easily import all needed classes with a simple action.

answered Sep 19 '14 at 17:17

M A

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Teach me to use a IDE and automatically use "Organize imports" when testing code from SO. All worked fine. – Jonathan Drapeau Sep 19 '14 at 17:20
Ok, so * only includes immediate child imports, rather than just EVERYTHING in awt? Good to know, thank you! I am using eclipse, what's the simple action I need to do? – Caleb Jay Sep 19 '14 at 17:28
It's a good practice to explicitly import the individual classes you need (see [this post](http://stackoverflow.com/questions/147454/why-is-using-a-wild-card-with-a-java-import-statement-bad)). In Eclipse, the shortcut on Windows is Ctrl+Shift+O. – M A Sep 19 '14 at 17:29

Why can't I implement two ActionListeners on two inner classes?

1 Answers1