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();
}
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