MouseListener 介面

public interface MouseListener
   void mousePressed(MouseEvent event);
      //Called when a mouse button has been pressed on a component
   void mouseReleased(MouseEvent event);
      //Called when a mouse button has been released on a component
   void mouseClicked(MouseEvent event);
      //Called when the mouse has been clicked on a component
   void mouseEntered(MouseEvent event);
      //Called when the mouse enters a component 
   void mouseExited(MouseEvent event);
      //Called when the mouse exits a component 
File MouseSpy.java
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
   This listener simply prints out the listener method name
   and the x- and y-coordinate of the mouse position.
public class MouseSpy implements MouseListener
   public void mousePressed(MouseEvent event)
      System.out.println("Mouse pressed. x = "
         + event.getX() + " y = " + event.getY());
   public void mouseReleased(MouseEvent event)
      System.out.println("Mouse released. x = "
         + event.getX() + " y = " + event.getY());
   public void mouseClicked(MouseEvent event)
      System.out.println("Mouse clicked. x = "
         + event.getX() + " y = " + event.getY());
   public void mouseEntered(MouseEvent event)
      System.out.println("Mouse entered. x = "
         + event.getX() + " y = " + event.getY());
   public void mouseExited(MouseEvent event)
      System.out.println("Mouse exited. x = "
         + event.getX() + " y = " + event.getY());
File MouseSpyApplet.java
import java.applet.Applet;
   This applet installs a mouse spy. Try generating the
   five mouse event types by moving and clicking the mouse.
public class MouseSpyApplet extends Applet
   public MouseSpyApplet()
      MouseSpy listener = new MouseSpy();
      addMouseListener(listener);
   class MousePressListener implements MouseListener
      public void mousePressed(MouseEvent event)
         int x = event.getX();
         int y = event.getY();
         box.setLocation(x,y);
         repaint(); 
      //do-nothing methods 
      public void mouseReleased(MouseEvent event){}
      public void mouseClicked(MouseEvent event){}
      public void mouseEntered(MouseEvent event){}
      public void mouseExited(MouseEvent event){}
   MouseListener listener = new MousePressListener();
   addMouseListener(listener);
The Mouse Applet
MouseApplet.java
import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
   This applet lets the user move a rectangle by clicking
   the mouse.
public class MouseApplet extends Applet
   public MouseApplet()
      // the rectangle that the paint method draws
      box = new Rectangle(BOX_X, BOX_Y,
         BOX_WIDTH, BOX_HEIGHT);
      // add mouse press listener
      class MousePressListener implements MouseListener
         public void mousePressed(MouseEvent event)
            int x = event.getX();
            int y = event.getY();
            box.setLocation(x, y);
            repaint();
         // do-nothing methods
         public void mouseReleased(MouseEvent event) {}
         public void mouseClicked(MouseEvent event) {}
         public void mouseEntered(MouseEvent event) {}
         public void mouseExited(MouseEvent event) {}
      MouseListener listener = new MousePressListener();
      addMouseListener(listener);
   public void paint(Graphics g)
      Graphics2D g2 = (Graphics2D)g;
      g2.draw(box);
   private Rectangle box;
   private static final int BOX_X = 100;
   private static final int BOX_Y = 100;
   private static final int BOX_WIDTH = 20;
   private static final int BOX_HEIGHT = 30;
  
JTextField xField = new JTextField(width);
  
JLabel xLabel = new JLabel("x = ");
  
Icon buttonIcon = new ImageIcon("hand.gif");

  
moveButton = new JButton("Move", buttonIcon); 
按鈕聽候者
  
按下按鈕, 即移動長方形
  
從含蓋的適用範圍讀取 xField, yField 變數 
public ButtonApplet()
   class MoveButtonListener implements ActionListener
      public void actionPerformed(ActionEvent event)
         int x =Integer.parseInt(xField.getText());
         int y =Integer.parseInt(yField.getText());
         box.setLocation(x,y);
         repaint();
   ActionListener listener = new MoveButtonListener();
   moveButton.addActionListener(listener);
在面板中放置元件
  
JPanel 是元件的容器(container)
  
在面板中添加元件
JPanel panel = new JPanel();
panel.add(xLabel);
panel.add(xField);
. . .
  
將面板放入框架(frame)
JFrame frame = new JFrame();
frame.setContentPane(panel);
  
裝填框架: 調整框架大小,
  剛好容得下這些元件
frame.pack();
frame.show();
 
File ButtonApplet.java
import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
   This applet lets the user move a rectangle by specifying
   the x- and y-position of the top left corner.
public class ButtonApplet extends Applet
   public ButtonApplet()
      // the rectangle that the paint method draws
      box = new Rectangle(BOX_X, BOX_Y,
         BOX_WIDTH, BOX_HEIGHT);
      // the text fields for entering the x- and y-coordinates
      final JTextField xField = new JTextField(5);
      final JTextField yField = new JTextField(5);
      // the button to move the rectangle
      JButton moveButton = new JButton("Move",
          new ImageIcon("hand.gif"));
      class MoveButtonListener implements ActionListener
         public void actionPerformed(ActionEvent event)
            int x = Integer.parseInt(xField.getText());
            int y = Integer.parseInt(yField.getText());
            box.setLocation(x, y);
            repaint();
      ActionListener listener = new MoveButtonListener();
      moveButton.addActionListener(listener);
      // the labels for labeling the text fields
      JLabel xLabel = new JLabel("x = ");
      JLabel yLabel = new JLabel("y = ");
      // the panel for holding the user interface components
      JPanel panel = new JPanel();
      panel.add(xLabel);
      panel.add(xField);
      panel.add(yLabel);
      panel.add(yField);
      panel.add(moveButton);
      // the frame for holding the component panel
      JFrame frame = new JFrame();
      frame.setContentPane(panel);
      frame.pack();
      frame.show();
   public void paint(Graphics g)
      Graphics2D g2 = (Graphics2D)g;
      g2.draw(box);
   private Rectangle box;
   private static final int BOX_X = 100;
   private static final int BOX_Y = 100;
   private static final int BOX_WIDTH = 20;
   private static final int BOX_HEIGHT = 30;
10.4 行為類似的按鈕組
有按鈕組的小程式
    JButton leftButton = new JButton("Left");
   class LeftButtonListener implements ActionListener
      public void actionPerformed(ActionEvent event)
         box.setLocation(-BOX_WIDTH,0);
         repaint();
   LeftButtonListener leftListener = new ButtonListener();
   leftButton.addActionListener(leftListener);
  
各個按鈕的程式碼只有在按鈕標記和移動量。
  
補救: 設計一方法, 可建構四個按鈕中任一個, 而將按鈕標記和移動量當做參數。
public JButton makeButton(String label, final int dx, final int dy)
   JButton button = new JButton(label);
   class ButtonListener implements ActionListener
      public void actionPerformed(ActionEvent event)
         box.translate(dx, dy);
         repaint();
   ButtonListener listener = new ButtonListener();
   button.addActionListener(listener);
   return button;
  
注意: 參數 dx 和 dy 宣告為 final。
  
如此, ButtonListener 才能夠存取這些參數。
  
呼用 makeButton 方法四次:
panel.add(makeButton("Left",-BOX_WIDTH,0));
panel.add(makeButton("Right",BOX_WIDTH,0));
panel.add(makeButton("Up",0,-BOX_HEIGHT));
panel.add(makeButton("Down",0,BOX_HEIGHT));
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
   This applet lets the user move a rectangle by clicking
   on buttons labeled "Left", "Right", "Up", and "Down".
public class ButtonApplet extends Applet
   public ButtonApplet()
      // the rectangle that the paint method draws
      box = new Rectangle(BOX_X, BOX_Y,
         BOX_WIDTH, BOX_HEIGHT);
      // the panel for holding the user interface components
      JPanel panel = new JPanel();
      panel.add(makeButton("Left", -BOX_WIDTH, 0));
      panel.add(makeButton("Right", BOX_WIDTH, 0));
      panel.add(makeButton("Up", 0, -BOX_HEIGHT));
      panel.add(makeButton("Down", 0, BOX_HEIGHT));
      // the frame for holding the component panel
      JFrame frame = new JFrame();
      frame.setContentPane(panel);
      frame.pack();
      frame.show();
   public void paint(Graphics g)
      Graphics2D g2 = (Graphics2D)g;
      g2.draw(box);
      Makes a button that moves the box.
      @param label the label to show on the button
      @param dx the amount by which to move the box in x-direction
      when the button is clicked
      @param dy the amount by which to move the box in y-direction
      when the button is clicked
      @return the button
   public JButton makeButton(String label, final int dx,
      final int dy)
      JButton button = new JButton(label);
      class ButtonListener implements ActionListener
         public void actionPerformed(ActionEvent event)
            box.translate(dx, dy);
            repaint();
      ButtonListener listener = new ButtonListener();
      button.addActionListener(listener);
      return button;
   private Rectangle box;
   private static final int BOX_X = 100;
   private static final int BOX_Y = 100;
   private static final int BOX_WIDTH = 20;
   private static final int BOX_HEIGHT = 30;
10.5 框架視窗
  
應用程式, 不是小程式

  
建構並顯示框架
JFrame frame = new JFrame();
. . .
frame.show();
  
設定預設的關閉運算
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
  
將元件加入面板, 然後將面板設為內容格(pane)
JPanel panel = new
  JPanel();
panel.add(. . .);
panel.add(. . .)
frame.setContentPane(panel);
 
A Frame with Two Labels
File FrameTest.java
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
   This program displays a frame with an image and a text label.
public class FrameTest
   public static void main(String[] args)
      JFrame frame = new JFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      JLabel iconLabel = new JLabel(new ImageIcon("world.gif"));
      JLabel textLabel = new JLabel("Hello, World!");
      JPanel panel = new JPanel();
      panel.add(iconLabel);
      panel.add(textLabel);
      frame.setContentPane(panel);
      frame.pack();
      frame.show();
10.6 文字元件
  
JTextField 容納單行文字
  
JTextArea 容納多行文字
  
用 new JTextArea(rows, columns) 建構
  
textArea.append(aString) 在末尾添附文字

  
textArea.setEditable(false) 只用於顯示
  
添加卷軸滑桿(scroll bar), 用
JScrollPane scrollPane = new JScrollPane(textArea);
textArea.setContentPane(scrollPane);
 
A Text Area with Scroll Bars
The Control Panel for Adding Interest
File TextAreaTest.java
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
   This program shows a frame with a text area that displays
   the growth of an investment. A second frame holds a text
   field to specify the interest rate.
public class TextAreaTest
   public static void main(String[] args)
      // the application adds interest to this bank account
      final BankAccount account = new BankAccount(INITIAL_BALANCE);
      // the text area for displaying the results
      final JTextArea textArea = new JTextArea(10, 30);
      textArea.setEditable(false);
      JScrollPane scrollPane = new JScrollPane(textArea);
      // construct the frame for displaying the text area
      JFrame frame = new JFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setContentPane(scrollPane);
      frame.pack();
      frame.show();
      // the label and text field for entering the interest rate
      JLabel rateLabel = new JLabel("Interest Rate: ");
      final JTextField rateField = new JTextField(10);
      rateField.setText("" + DEFAULT_RATE);
      // the button to trigger the calculation
      JButton calculateButton = new JButton("Add Interest");
      class CalculateListener implements ActionListener
         public void actionPerformed(ActionEvent event)
            double rate = Double.parseDouble(
               rateField.getText());
            double interest = account.getBalance()
               * rate / 100;
            account.deposit(interest);
            textArea.append(account.getBalance() + "\n");
      ActionListener listener = new CalculateListener();
      calculateButton.addActionListener(listener);
      // the control panel that holds the input components
      JPanel controlPanel = new JPanel();
      controlPanel.add(rateLabel);
      controlPanel.add(rateField);
      controlPanel.add(calculateButton);
      // the frame to hold the control panel
      JFrame controlFrame = new JFrame();
      controlFrame.setContentPane(controlPanel);
      controlFrame.pack();
      controlFrame.show();