isSelected() - Getting State of Check Box

Java Swing Tutorials - Herong's Tutorial Examples

∟isSelected() - Getting State of Check Box

This section provides a tutorial example on how to use the isSelected() method to know the state of a check box.

If you are using multiple check boxes, you need to keep track of them and use the isSelected() method to get the state of each of them. Here is a sample program:

/* JCheckBoxAction.java
 * Copyright (c) 1997-2024 HerongYang.com. All Rights Reserved.
 */
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JCheckBoxAction implements ActionListener {
   JCheckBox red; 
   JCheckBox green; 
   JCheckBox blue;
   JLabel myLabel = null;
   public static void main(String[] a) {
      JCheckBoxAction myTest = new JCheckBoxAction();
      myTest.createFrame();
   }
   public void createFrame() {
      JFrame f = new JFrame("My Check Boxes");
      f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      Container c = f.getContentPane();
      c.setLayout(new BoxLayout(c,BoxLayout.Y_AXIS));
      JPanel p = new JPanel();
      p.setLayout(new GridLayout(3,1));

    red = new JCheckBox("Red");
      green = new JCheckBox("Green");
      blue = new JCheckBox("Blue");
      p.add(red);
      p.add(green);
      p.add(blue);
    
      c.add(p);
      JButton b = new JButton("Done");
      b.addActionListener(this);
      c.add(b);
      myLabel = new JLabel("Please select",SwingConstants.CENTER);
      c.add(myLabel);
      f.pack();
      f.setVisible(true);
   }
   public void actionPerformed(ActionEvent e) {
    String t = "";
    if (red.isSelected()) t += "Red ";
    if (green.isSelected()) t += "Green ";
    if (blue.isSelected()) t += "Blue ";
    if (t.equals("")) t = "Nothing selected";
      myLabel.setText(t);
   }
}

If you run this program, you will see none of the check boxes is selected initially. If you click "Done", you will get the "Nothing selected" message. If you select some check boxes, then click "Done", you will get all selected items: