Java AWT GridBagLayout用法及代碼示例

// Java program to demonstrate GridBagLayout class.
import java.awt.*;
import java.awt.event.*;
import javax.swing.JFrame;
import javax.swing.*;
// class extends JFrame
public class GridbagDemo extends JFrame {
    GridbagDemo()
    {
        // Function to set title of JFrame.
        setTitle("GridBagLayoutDemo");
        // Creating Object of Jpanel class
        JPanel p = new JPanel();
        // set the layout
        p.setLayout(new GridBagLayout());
        // creates a constraints object
        GridBagConstraints c = new GridBagConstraints();
        // insets for all components
        c.insets = new Insets(2, 2, 2, 2);
        // column 0
        c.gridx = 0;
        // row 0
        c.gridy = 0;
        // increases components width by 10 pixels
        c.ipadx = 15;
        // increases components height by 50 pixels
        c.ipady = 50;
        // constraints passed in
        p.add(new JButton("Java Swing"), c);
        // column 1
        c.gridx = 1;
        // increases components width by 70 pixels
        c.ipadx = 90;
        // increases components height by 40 pixels
        c.ipady = 40;
        // constraints passed in
        p.add(new JButton("Layout"), c);
        // column 0
        c.gridx = 0;
        // row 2
        c.gridy = 1;
        // increases components width by 20 pixels
        c.ipadx = 20;
        // increases components height by 20 pixels
        c.ipady = 20;
        // constraints passed in
        p.add(new JButton("Manager"), c);
        // increases components width by 10 pixels
        c.ipadx = 10;
        // column 1
        c.gridx = 1;
        // constraints passed in
        p.add(new JButton("Demo"), c);
        // Creating Object of "wndcloser" 
        // class of windowlistener
        WindowListener wndCloser = new WindowAdapter() {
            public void windowClosing(WindowEvent e)
            {
                // exit the system
                System.exit(0);
            }
        };
        // add the actionwindowlistener
        addWindowListener(wndCloser);
        // add the content
        getContentPane().add(p);
        // Function to set size of JFrame.
        setSize(600, 400);
        // Function to set visibility of JFrame.
        setVisible(true);
    }
    // Main Method
    public static void main(String[] args)
    {
        // calling the constructor
        new GridbagDemo();
    }
}

// Java program to demonstrate GridBagLayout class.
import java.awt.*;
import javax.swing.JButton;
import javax.swing.JFrame;
  
// Constructor of GridBagLayout class.
public class GridBagLayoutDemo {
  
    final static boolean shouldFill = true;
    final static boolean shouldWeightX = true;
    final static boolean RIGHT_TO_LEFT = false;
  
public static void addComponentsToPane(Container pane)
{
    // if condition
    if (RIGHT_TO_LEFT) {
        pane.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
    }
    // Declaration of objects of JButton class
    JButton button;
    // set the layout
    pane.setLayout(new GridBagLayout());
    // creates a constraints object
    GridBagConstraints c = new GridBagConstraints();
    // if condition
    if (shouldFill) {
        // natural height, maximum width
        c.fill = GridBagConstraints.HORIZONTAL;
    }
    // Initialization of object 
    // "button" of JButton class.
    button = new JButton("Button 1");
    // if condition
    if (shouldWeightX) {
        c.weightx = 0.5;
    }
    // column 0
    c.gridx = 0;
    // row 0
    c.gridy = 0;
    // Adding JButton "button" on JFrame.
    pane.add(button, c);
    // Initialization of object
    // "button" of JButton class.
    button = new JButton("Button 2");
    // column 1
    c.gridx = 1;
    // row 0
    c.gridy = 0;
    // Adding JButton "button" on JFrame.
    pane.add(button, c);
    // Initialization of object
    // "button" of JButton class.
    button = new JButton("Button 3");
    // column 1
    c.gridx = 2;
    // row 0
    c.gridy = 0;
    // Adding JButton "button" on JFrame.
    pane.add(button, c);
    // Initialization of object 
    // "button" of JButton class.
    button = new JButton("Long-Named Button 4");
    // increases components height by 40 pixels
    c.ipady = 40;
    // column width 0
    c.weightx = 0.0;
    // row width 3
    c.gridwidth = 3;
    // column 1
    c.gridx = 0;
    // row 1
    c.gridy = 1;
    // Adding JButton "button" on JFrame.
    pane.add(button, c);
    // Initialization of object 
    // "button" of JButton class.
    button = new JButton("Button 5");
    // increases components height by 0 pixels
    c.ipady = 0;
    // request any extra vertical space
    c.weighty = 1.0;
    // bottom of space
    c.anchor = GridBagConstraints.PAGE_END;
    // top padding
    c.insets = new Insets(10, 0, 0, 0);
    // column 2
    c.gridx = 1;
    // 2 columns wide
    c.gridwidth = 2;
    // row 3
    c.gridy = 2;
    // Adding JButton "button" on JFrame.
    pane.add(button, c);
}
// Create the GUI and show it.  For thread safety,
// this method should be invoked from the
// event-dispatching thread.
private static void createAndShowGUI()
{
    // to set a Jframe default
    JFrame.setDefaultLookAndFeelDecorated(true);
    // Create and set up the window.
    JFrame frame = new JFrame("GridBagLayoutDemo");
    // Function to close the operation of JFrame.
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    // adding the content pane.
    addComponentsToPane(frame.getContentPane());
    // Display the window.
    frame.pack();
    // Function to set visible status of JFrame.
    frame.setVisible(true);
}
    // Main Method
    public static void main(String[] args)
    {
  
        // Schedule a job for the event-dispatching thread:
        // creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
  
            public void run()
            {
                createAndShowGUI();
            }
        });
    }
}