Container
- A Container class can be described as a special component that can hold the gathering of the components.
- There are two types of Swing Containers, they are top-level containers and low-level containers.
- Top-Level containers are heavyweight containers such as JFrame, JApplet, JWindow, and JDialog.
- Low-Level containers are lightweight containers such as JPanel.
- The most commonly used containers are JFrame, JPanel and JWindow.
- The important methods of the Container class are add(), invalidate() and validate().
Example
import java.awt.*;
import javax.swing.*;
public class ContainerTest extends JFrame { // top-level container
JPanel panel; // low-level container
JTextField field;
JButton btn;
public ContainerTest() {
setTitle("Container Test");
panel = new JPanel();
field = new JTextField(20);
panel.add(field);
btn = new JButton("Submit");
panel.add(btn);
add(panel, BorderLayout.CENTER);
setSize(350, 275);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
}
public static void main(String args[]) {
new ContainerTest();
}
}
Output
