Container Event in java programming (V67)

ContainerEvent

ContainerEvent is a class in Java that represents an event indicating that a component has been added to or removed from a container (such as Panel, JPanel, Frame, etc.).

Example:

Source Code:

Copied!

    public ContainerEventSwingDemo() {
        initComponents();
        // Add ContainerListener to jPanel1
         jPanel1.setLayout(new java.awt.FlowLayout());

        // Add ContainerListener
        jPanel1.addContainerListener(new java.awt.event.ContainerListener() {
            @Override
            public void componentAdded(java.awt.event.ContainerEvent e) {
                System.out.println("Component added: " + e.getChild());
            }

            @Override
            public void componentRemoved(java.awt.event.ContainerEvent e) {
                System.out.println("Component removed: " + e.getChild());
            }
        });
    }                                                

Source Code: Button Add

Copied!

    private int labelCount = 1;
    private void btnAddActionPerformed(java.awt.event.ActionEvent evt) {                                       
        javax.swing.JLabel lbl = new javax.swing.JLabel("Label " + labelCount++);
    jPanel1.add(lbl);
    jPanel1.revalidate(); // re-layout the container
    jPanel1.repaint();    // redraw the container
    }                                                 

Source Code: Button Remove 

Copied!

    private void btnRemoveActionPerformed(java.awt.event.ActionEvent evt) {                                          
        if (jPanel1.getComponentCount() > 0) {
        jPanel1.remove(0);
        jPanel1.revalidate();
        jPanel1.repaint();
         }
    }                                                           

Result:

Watch the video:

Ebook: https://softkhpc.blogspot.com/2025/05/java-programming-ebooks.html