Thursday, May 22, 2014

how to use checkbox in java?





A check box provides a way to make a single on/off choice. It consists of a tiny box and a label. The box typically holds a little “x” (or some other indication that it is set) or is empty, depending on whether that item was selected.   You’ll normally create a JCheckBox using a constructor that takes the label as an argument. You can get and set the state, and also get and set the label if you want to read or change it after the JCheckBox has been created.  Whenever a JCheckBox is set or cleared, an event occurs, which you can capture the same way you do a button by using an ActionListener.

                      The following example uses a JTextArea to enumerate all the check boxes that have been checked. The trace( ) method sends the name of the selected JCheckBox and its current state to the JTextArea using append( ), so you’ll see a cumulative list of the checkboxes that were selected and what their state is.



CheckBoxes.java
 
import javax.swing.*;

import java.awt.event.*;

import java.awt.*;



public class CheckBoxes extends JFrame {

private JTextArea t = new JTextArea(6, 15);

private JCheckBox

cb1 = new JCheckBox("Check Box 1"),

cb2 = new JCheckBox("Check Box 2"),

cb3 = new JCheckBox("Check Box 3");

CheckBoxes() {

super("CheckBox Demo");

cb1.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

trace("1", cb1);

}

});

cb2.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

trace("2", cb2);

}

});

cb3.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

trace("3", cb3);

}

});

Container cp = getContentPane();

cp.setLayout(new FlowLayout());

cp.add(new JScrollPane(t));

cp.add(cb1);

cp.add(cb2);

cp.add(cb3);

}

private void trace(String b, JCheckBox cb) {

if(cb.isSelected())

t.append("Box " + b + " Set\n");

else

t.append("Box " + b + " Cleared\n");

}

public static void main(String[] args) {

CheckBoxes chkbox= new CheckBoxes();

//chkbox.setSize(300,300);

chkbox.pack();

chkbox.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

chkbox.setVisible(true);



}

}


OUTPUT:-