JPanel
- A JPanel is a subclass of JComponent (a subclass of a Container class). Therefore, JPanel is also a Container.
- A JPanel is an empty area that can be used either to layout other components including other panels.
- In a JPanel, we can add fields, labels, buttons, checkboxes, and images also.
- The Layout Managers such as FlowLayout, GridLayout, BorderLayout and other layout managers helps us to control the sizes, positions, and alignment of the components using JPanel.
- The important methods of a JPanel class are getAccessibleContext(), getUI(), updateUI() and paramString().
- We can also implement a JPanel with vertical and horizontal scrolls by adding the panel object to JScrollPane.
Example
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JScrollablePanelTest extends JFrame {
public JScrollablePanelTest() {
setTitle("JScrollablePanel Test");
setLayout(new BorderLayout());
JPanel panel = createPanel();
add(BorderLayout.CENTER, new JScrollPane(panel));
setSize(375, 250);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
}
public static JPanel createPanel() {
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(10, 4, 10, 10));
for (int i=0; i < 10; i++) {
for (int j=0; j < 4; j++) {
JLabel label = new JLabel("label " + i + ", " + j);
label.setFont(new Font("Arial", Font.PLAIN, 20));
panel.add(label);
}
}
return panel;
}
public static void main(String [] args) {
new JScrollablePanelTest();
}
}
Output
