Java2实用教程（第三版）课后答案 - 耿祥义主编

buttonRed.setBounds(10,170,50,30); add(buttonGreen);

buttonGreen.setBounds(70,170,50,30); add(buttonBlue);

buttonBlue.setBounds(130,170,50,30); buttonRed.addActionListener(this); buttonGreen.addActionListener(this); buttonBlue.addActionListener(this); addWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e) {

System.exit(0); } } );

setBounds(100,100,200,250); setVisible(true); validate(); }

public void actionPerformed(ActionEvent e) {

if(e.getSource()==buttonRed) {

canvas.setX(1); canvas.repaint(); }

else if(e.getSource()==buttonGreen) {

canvas.setX(2); canvas.repaint(); }

else if(e.getSource()==buttonBlue) {

canvas.setX(3);

canvas.repaint(); } } }

class Mycanvas extends Canvas {

int x=0; Mycanvas()

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{

setBackground(Color.white); }

public void setX(int y) { x=y; }

public void paint(Graphics g) {

switch(x){ case 1:

g.setColor(Color.red); break; case 2:

g.setColor(Color.green); break; case 3:

g.setColor(Color.blue); break; default:

g.setColor(Color.white); }

g.drawOval(65,65,50,50); } }

public class Test {

public static void main(String args[]) {

new WindowChangeColor(\改变颜色\} }

14.编写应用程序，测试Cursor类中表示鼠标形状的静态常量。 答: import java.awt.*; import java.awt.event.*;

class WindowCursor extends Frame implements ActionListener {

Button button,button1; TextField text; int n=-1;

WindowCursor() {

button=new Button(\单击我\

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text=new TextField(\将鼠标放在上面的按钮上看形状\button1=new Button(\看看你鼠标的形状\add(button,BorderLayout.NORTH); add(button1,BorderLayout.CENTER); add(text,BorderLayout.SOUTH);

button.setBackground(Color.cyan); button1.setBackground(Color.pink); button.addActionListener(this);

addWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e) {

System.exit(0); } } );

setBounds(100,100,190,150); setVisible(true); validate(); }

public void actionPerformed(ActionEvent e) {

n=(n+1); switch(n) {

case 0:

button1.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR)); break; case 1:

button1.setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));

break; case 2:

button1.setCursor(Cursor.getPredefinedCursor(Cursor.TEXT_CURSOR)); break; case 3:

button1.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR)); break;

case 4:

button1.setCursor(Cursor.getPredefinedCursor(Cursor.N_RESIZE_CURSOR));

break; case 5:

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button1.setCursor(Cursor.getPredefinedCursor(Cursor.NW_RESIZE_CURSOR));

break; case 6:

button1.setCursor(Cursor.getPredefinedCursor(Cursor.NE_RESIZE_CURSOR));

break; case 7:

button1.setCursor(Cursor.getPredefinedCursor(Cursor.W_RESIZE_CURSOR));

break; case 8:

button1.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR)); break; case 9:

button1.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR)); break; } } }

public class Test {

public static void main(String args[]) {

new WindowCursor(); } }

15.改进本章例子7.30，当释放鼠标键时，如果当前组件和其他组件相交，就将其他组件设置为不可见状态。 答: import java.awt.*; import java.awt.event.*;

import javax.swing.SwingUtilities;

class Win extends Frame implements MouseListener,MouseMotionListener {

Button button; TextField text; int x,y;

boolean move=false; Win() {

button=new Button(\用鼠标拖动我\text=new TextField(\用鼠标拖动我\text.setBackground(Color.green);

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