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); button.setBackground(Color.blue); button.addMouseListener(this); button.addMouseMotionListener(this); text.addMouseListener(this); text.addMouseMotionListener(this); addMouseMotionListener(this); setLayout(new FlowLayout()); add(button); add(text);
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0); } } );
setBounds(10,10,350,300); setVisible(true); validate(); }
public void mousePressed(MouseEvent e){} public void mouseReleased(MouseEvent e) {
move=false;
Rectangle rect=button.getBounds(); int x=(int)rect.getX(); int y=(int)rect.getY();
if(rect.intersects(text.getBounds())) {
if(e.getSource()==button) {
text.setVisible(false); }
else if(e.getSource()==text) {
button.setVisible(false); } } }
public void mouseEntered(MouseEvent e){} public void mouseExited(MouseEvent e){} public void mouseClicked(MouseEvent e){} public void mouseMoved(MouseEvent e){} public void mouseDragged(MouseEvent e) {
Component com=null;
if(e.getSource() instanceof Component) {
com=(Component)e.getSource(); if(com!=this) move=true;
e=SwingUtilities.convertMouseEvent(com,e,this); if(move) {
x=e.getX(); y=e.getY();
int w=com.getSize().width , h=com.getSize().heig ht; com.setLocation(x-w/2,y-h/2); } } } }
public class Test {
public static void main(String args[]) {
Win win=new Win(); } }
16.进一步改进本章例子7.33，要求一个按钮在移动时，不允许和其他按钮相交。 答: import java.awt.*; import java.awt.event.*;
class Win extends Frame implements KeyListener {
Button b[]=new Button[8]; int x,y; Win() {
setLayout(new FlowLayout()); for(int i=0;i<8;i++) {
b[i]=new Button(\b[i].addKeyListener(this); add(b[i]); }
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0); }
} );
setBounds(10,10,300,300); setVisible(true); validate(); }
public void keyPressed(KeyEvent e) {
boolean move=false;
Button button=(Button)e.getSource(); Rectangle buttonrect=button.getBounds(); String str=button.getLabel(); int xx=Integer.parseInt(str); x=button.getBounds().x; y=button.getBounds().y;
if(e.getKeyCode()==KeyEvent.VK_UP) { y=y-2; if(y<=0) y=0; }
else if(e.getKeyCode()==KeyEvent.VK_DOWN) { y=y+2;
if(y>=300) y=300; }
else if(e.getKeyCode()==KeyEvent.VK_LEFT) { x=x-2; if(x<=0) x=0; }
else if(e.getKeyCode()==KeyEvent.VK_RIGHT) { x=x+2;
if(x>=300) x=300; }
buttonrect.setLocation(x,y); for(int k=0;k<8;k++) {
Rectangle rect=b[k].getBounds();
if((buttonrect.intersects(rect))&&(xx!=k)) {
move=true; } }
if(move==false) {
button.setLocation(x,y); } }
public void keyTyped(KeyEvent e){} public void keyReleased(KeyEvent e){} }
public class Test {
public static void main(String args[]) {
Win win=new Win(); } }
第8 章建立对话框
1. 编写一个应用程序，用户可以在一个文本框里输入数字字符，按Ente r 键后将数字放入一个文本区。 当输入的数字大于100 0 时，弹出一个有模式的对话框，提示用户数字已经大于1000，是否继续将该数 字放入文本区。
答: import java.awt.event.*; import java.awt.*;
import javax.swing.JOptionPane;
class WindowSaveNumber extends Frame implements ActionListener {
TextField textInputNumber; TextArea textSaveNumber; WindowSaveNumber() {
textInputNumber=new TextField(15); textSaveNumber=new TextArea();
add(textInputNumber,BorderLayout.NORTH);