Text Box not working properly

Question

I wrote a program for an applet that is supposed to display different text in a text box when you push a button. My program has no errors when I compiled it, but the text box doesn't display correctly. I don't know what is wrong with it. Here is my code

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

public class colors{
Button button1;
Button button2;
Button button3;
Label label1;
TextField objTextField1; 

public static void main (String args[]){
colors c = new colors();
}
public colors() {
Frame f = new Frame ("Colors");
Button button1 = new Button("Blue");
button1.setBounds(10,305,120,75);
button1.addMouseListener(new MyMouseListener1());
Button button2 = new Button("Red");
button2.setBounds(140,305,120,75);
button2.addMouseListener(new MyMouseListener2());
Button button3 = new Button("Yellow");
button3.setBounds(270,305,120,75);
button3.addMouseListener(new MyMouseListener3());

f.add(button1);
f.add(button2);
f.add(button3);

label1 = new Label("Click a Button to Reveal Text");
label1.setBounds(20,105,200,25);
f.add(label1);


objTextField1 = new TextField("Which Color?", 15);
objTextField1.setBounds(20,75,125,50);
f.add(objTextField1);

f.add(label1);
f.add(objTextField1);

f.addWindowListener(new WindowAdapter()
{
    public void windowClosing(WindowEvent we){
        System.exit(0);
    }
});
f.setSize(400,400);
f.setVisible(true);
}
public class MyMouseListener1 extends MouseAdapter{
        public void mouseClicked(MouseEvent me){
            objTextField1.setText("Blue");
        }
    }
public class MyMouseListener2 extends MouseAdapter{
        public void mouseClicked(MouseEvent me){
            objTextField1.setText("Red");
        }
}

public class MyMouseListener3 extends MouseAdapter{
    public void mouseClicked(MouseEvent me){
        objTextField1.setText("Yellow");
        }
    }
}

You should be using [Swing components](http://docs.oracle.com/javase/tutorial/uiswing/components/index.html) instead of AWT components — Paul Samsotha, Jul 27 '14 at 04:44
I tested your code and it's working as expected. ?*the text box doesn't display correctly* what do you mean by this line? — Braj, Jul 27 '14 at 05:03

score 2 · Answer 1 · answered Jul 27 '14 at 04:22

When a Button is clicked it fires an ActionEvent.

You should use an ActionListener instead of a MouseListener.

public void actionPerformed(ActionEvent e) { 
    ...//code that reacts to the action... 
}

AND don't forget to add

button.addActionListener(instance);

score 1 · Answer 2 · edited May 23 '17 at 12:14

I have tested your code and it's working as expected but I have noticed some of the points in your code as mentioned below:

Use setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) instead of System.exit(0) and adding WindowListener to close the window.
Use frame.pack() instead of frame.setSize() that fits the components as per component's preferred size.
Don't use null layout and never use absolute positioning via calling setBounds() instead use a proper Layout Manager that suits as per your application design.

Read more How to Use Various Layout Managers
Use SwingUtilities.invokeLater() or EventQueue.invokeLater() to make sure that EDT is initialized properly.

Read more
Follow Java Naming convention
Keep the instance members private
This is already addressed by @TAsk that you should be using ActionListener instead of MouseListener if you are interested in only mouseClicked() method.
You should be using Swing components instead of AWT components as already mentioned by @peeskillet

score 1 · Answer 3 · answered Jul 27 '14 at 13:18

To make an applet you should extend javax.swing.JApplet class & override init() method.

To change the color, you must write your logics in actionPerformed() of ActionListener. But it's an interface. So, you can make use of Anonymous Inner class & implement actionPerformed() in it.

So, when you call addActionListener() on a JButton, I recommend you to do that by using Anonymous Inner class. It would be more clear through following code.

My Suggestion: Whenever you write code, always keep OOD principles in your mind. This isn't right place to discuss that, but your code has a Code smell which is Duplication in code.

Below is the best way to do what you want & we're also using DRY Principle.

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JPanel;

public class ColorChanger extends javax.swing.JApplet {

    private JPanel mainPanel;

    private JButton btnRed;
    private JButton btnGreen;
    private JButton btnBlue;

    @Override
    public void init() {
        super.init();
        mainPanel = new JPanel();

        btnRed = new JButton("Red");
        btnGreen = new JButton("Green");
        btnBlue = new JButton("Blue");

        this.add(mainPanel);
        mainPanel.add(btnRed);
        mainPanel.add(btnGreen);
        mainPanel.add(btnBlue);

        bindActionEvent(btnRed, Color.RED);
        bindActionEvent(btnGreen, Color.GREEN);
        bindActionEvent(btnBlue, Color.BLUE);

    }

    private void bindActionEvent(JButton b1, Color color) {

        b1.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                mainPanel.setBackground(color);
                //Write setText() for your TextField here.
            }
        });
    }       //END Of Helper Method
}

Text Box not working properly

3 Answers3