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AWT ContainerListener Interface
Introduction
The interfaceContainerListener is used for receiving container events. The class that process container events needs to implements this interface.
Class declaration
Following is the declaration for java.awt.event.ContainerListener interface:
public interface ContainerListener extends EventListener
Interface methods
S.N. | Method & Description |
---|---|
1 | void componentAdded(ContainerEvent e) Invoked when a component has been added to the container. |
2 | void componentRemoved(ContainerEvent e) Invoked when a component has been removed from the container. |
Methods inherited
This class inherits methods from the following interfaces:
java.awt.event.EventListener
ContainerListener Example
Create the following java program using any editor of your choice in say D:/ > AWT > com > tutorialspoint > gui >
AwtListenerDemo.javapackage com.tutorialspoint.gui; import java.awt.*; import java.awt.event.*; public class AwtListenerDemo { private Frame mainFrame; private Label headerLabel; private Label statusLabel; private Panel controlPanel; public AwtListenerDemo(){ prepareGUI(); } public static void main(String[] args){ AwtListenerDemo awtListenerDemo = new AwtListenerDemo(); awtListenerDemo.showContainerListenerDemo(); } private void prepareGUI(){ mainFrame = new Frame("Java AWT Examples"); mainFrame.setSize(400,400); mainFrame.setLayout(new GridLayout(3, 1)); mainFrame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent windowEvent){ System.exit(0); } }); headerLabel = new Label(); headerLabel.setAlignment(Label.CENTER); statusLabel = new Label(); statusLabel.setAlignment(Label.CENTER); statusLabel.setSize(350,100); controlPanel = new Panel(); controlPanel.setLayout(new FlowLayout()); mainFrame.add(headerLabel); mainFrame.add(controlPanel); mainFrame.add(statusLabel); mainFrame.setVisible(true); } private void showContainerListenerDemo(){ headerLabel.setText("Listener in action: ContainerListener"); ScrollPane panel = new ScrollPane(); panel.setBackground(Color.magenta); panel.addContainerListener(new CustomContainerListener()); Label msglabel = new Label(); msglabel.setAlignment(Label.CENTER); msglabel.setText("Welcome to TutorialsPoint AWT Tutorial."); panel.add(msglabel); controlPanel.add(panel); mainFrame.setVisible(true); } class CustomContainerListener implements ContainerListener { public void componentAdded(ContainerEvent e) { statusLabel.setText(statusLabel.getText() + e.getComponent().getClass().getSimpleName() + " added. "); } public void componentRemoved(ContainerEvent e) { statusLabel.setText(statusLabel.getText() + e.getComponent().getClass().getSimpleName() + " removed. "); } } }
Compile the program using command prompt. Go to D:/ > AWT and type the following command.
D:\AWT>javac com\tutorialspoint\gui\AwtListenerDemo.java
If no error comes that means compilation is successful. Run the program using following command.
D:\AWT>java com.tutorialspoint.gui.AwtListenerDemo
Verify the following output