Java AWT Checkbox

The Checkbox class is used to create a checkbox. It is used to turn an option on (true) or off (false). Clicking on a Checkbox changes its state from "on" to "off" or from "off" to "on".

Checkbox class is used to create a checkbox control, which contains a box that can be checked or unchecked by clicking on it.

public class Checkbox extends Component implements ItemSelectable, Accessible  

Checkbox Class Constructors:

1.    Checkbox()                                - It constructs a checkbox with no string as the label.

2.    Checkbox(String label)              - It constructs a checkbox with the given label.

3.    Checkbox(String label, boolean state)      - It constructs a checkbox with the given label and sets the given state.

4.    Checkbox(String label, boolean state, CheckboxGroup group)   - It constructs a checkbox with the given label, set the given state in the specified checkbox group.

5.    Checkbox(String label, CheckboxGroup group, boolean state)   - It constructs a checkbox with the given label, in the given checkbox group and set to the specified state.

Checkbox Class Methods:

1.      void addItemListener(ItemListener IL)    - It adds the given item listener to get the item events from the checkbox.

2.      AccessibleContext getAccessibleContext()       - It fetches the accessible context of checkbox.

3.      void addNotify()                                       - It creates the peer of checkbox.

4.      CheckboxGroup getCheckboxGroup()     - It determines the group of checkbox.

5.      ItemListener[] getItemListeners()             - It returns an array of the item listeners registered on checkbox.

6.      String getLabel()                                        -  It fetched the label of checkbox.

7.      T[] getListeners(Class listenerType)          - It returns an array of all the objects registered as FooListeners.

8.      Object[] getSelectedObjects()                   - It returns an array (size 1) containing checkbox label and returns null if checkbox is not selected.

9.      boolean getState()                                      - It returns true if the checkbox is on, else returns off.

10.    protected String paramString()                  - It returns a string representing the state of checkbox.

11.    protected void processEvent(AWTEvent e)      - It processes the event on checkbox.

12.    protected void processItemEvent(ItemEvent e)            - It process the item events occurring in the checkbox by dispatching them to registered ItemListener object.

13.    void removeItemListener(ItemListener l) - It removes the specified item listener so that the item listener doesn't receive item events from the checkbox anymore.

14.    void setCheckboxGroup(CheckboxGroup g)    - It sets the checkbox's group to the given checkbox.

15.    void setLabel(String label)                        - It sets the checkbox's label to the string argument.

16.    void setState(boolean state)                      - It sets the state of checkbox to the specified state.

Ex:

import java.awt.*;   

import java.awt.event.*;   

public class CheckboxExample2 

{   

// constructor to initialize  

     CheckboxExample2() {   

// creating the frame 

        Frame f = new Frame ("CheckBox Example");   

// creating the label 

        final Label label = new Label();           

// setting the alignment, size of label       

   label.setAlignment(Label.CENTER);   

        label.setSize(400,100);   

// creating the checkboxes 

        Checkbox checkbox1 = new Checkbox("C++");   

        checkbox1.setBounds(100, 100,  50, 50);   

        Checkbox checkbox2 = new Checkbox("Java");   

        checkbox2.setBounds(100, 150,  50, 50);   

// adding the checkbox to frame 

f.add(checkbox1); 

f.add(checkbox2);  

f.add(label);   

 // adding event to the checkboxes 

        checkbox1.addItemListener(new ItemListener() {   

             public void itemStateChanged(ItemEvent e) {                

                label.setText("C++ Checkbox: " + (e.getStateChange()==1?"checked":"unchecked"));   

             }   

          });   

        checkbox2.addItemListener(new ItemListener() {   

             public void itemStateChanged(ItemEvent e) {                

                label.setText("Java Checkbox: " + (e.getStateChange()==1?"checked":"unchecked"));   

             }   

          });   

// setting size, layout and visibility of frame 

        f.setSize(400,400);   

        f.setLayout(null);   

        f.setVisible(true);   

     }   

// main method 

public static void main(String args[])   

{   

    new CheckboxExample2();   

}   

}