10.4 在组件中显示信息

import javax.swing.*; import java.awt.*; /** * @version 1.33 2015-05-12 * @author Cay Horstmann */ public class NotHelloWorld { public static void main(String[] args) { EventQueue.invokeLater(() -> { JFrame frame = new NotHelloWorldFrame(); frame.setTitle("NotHelloWorld"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); }); } } /** * A frame that contains a message panel */ class NotHelloWorldFrame extends JFrame { public NotHelloWorldFrame() { add(new NotHelloWorldComponent()); pack(); } } /** * A component that displays a message. */ class NotHelloWorldComponent extends JComponent { public static final int MESSAGE_X = 75; public static final int MESSAGE_Y = 100; private static final int DEFAULT_WIDTH = 300; private static final int DEFAULT_HEIGHT = 200; public void paintComponent(Graphics g) { g.drawString("Not a Hello, World program", MESSAGE_X, MESSAGE_Y); } public Dimension getPreferredSize() { return new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT); } }