Thread: Can't set label text from a Jbutton

Hello all,

I have the following code. I would like to be able to set the text in the label (called label) to something else when a user click the close button.

I am guessing that my action class does not know what label is but I'm not sure how to reference since its in another class.

Thanks!!
VBGuy

package test;
 
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
public class Main {
 
    public static void main(String[] args) {
        ShowFrame();
    }
 
    public static void ShowFrame() {
 
        JFrame MyWindow = new JFrame("Hello World");
        MyWindow.setSize(800, 600);
        MyWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        MyWindow.setLayout(null);
 
        //Label
        JLabel label = new JLabel("Hello World!");
        label.setBounds(200, 10, 100, 25);
 
        //Text Field
        JTextField bbox = new JTextField(16);
        bbox.setBounds(10, 10, 100, 25);
 
        //Add Buttons
        JButton CloseButton = new JButton("Close");
        CloseButton.setBounds(10, 100, 90, 40);
 
        JButton OkButton = new JButton("Ok");
        OkButton.setBounds(100, 100, 90, 40);
 
        //Add to Frame
        MyWindow.add(CloseButton);
        MyWindow.add(bbox);
        MyWindow.add(OkButton);
        MyWindow.add(label);
 
        //Set Visible
        MyWindow.setVisible(true);
        bbox.setVisible(true);
        CloseButton.setVisible(true);
        OkButton.setVisible(true);
 
        //Set Action Listener
        CloseButton.addActionListener(new Action());
 
    }
}

package test;
 
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
public class Action implements ActionListener {
 
    public void actionPerformed(ActionEvent e) {
        label.setText("You Clicked Close!");
 
    }
}

Originally Posted by helloworld922

Yes, your intuition is correct. Action has no idea what label is. The easiest way to solve this problem is to pass label to it when it's being constructed:

public class Action implements ActionListener
{
    private JLabel label;
    public Action(JLabel label)
    {
        this.label = label;
    }
 
    public void actionPerformed(ActionEvent e)
    {
        label.setText("You Clicked Close!");
    }
}

Thanks Helloworld but I get an error when I try to run the code after your changes.

I get 'cannot find symbol'

Any thoughts?

Thanks!

I get an error

Please copy and paste full text of the error message here.
What symbol?

If you are getting compile errors, you must copy and paste them here. We're not able to see them otherwise.

What package does your Action class come from? I can only see an interface in javax.swing.
If you're making your own class, it'd be better not to use one of Sun's