buttons[count]=newJButton(names[count]);
container.add(buttons[count]);
}
this.setSize(300,150);
this.setVisible(true);
}
publicstaticvoidmain(Stringargs[]){
GridLayoutDemoapplication=newGridLayoutDemo();
}
}//endclassGridLayoutDemo
4、常用事件
基本组成:
1)、事件源EventSource:
能够触发事件控件如:
JButton,JTextField,JFrame,
JComboBox,....
2)、事件Event:
ActionEvent,KeyEvent,WindowEvent,TextEvent,...
3)、事件侦听者Listener(接口)
ActionListener,WindowListener,...
classAimplementsActionListener{
publicvoidactionPerformed(ActionEvente){
....
}
}
Alis=newA();
4)、事件处理函数
publicvoidactionPerformed(ActionEvente){
....
}
事件流程:
事件源触发事件-->事件源侦听者接收事件-->自动调用相应事件处理函数.
编程模板:
classMyFrmextendsJFrameimplementsActionListener{
JButtonbtn=newJButton("OK");
...
publicMyFrm(){
...
btn.addActionListner(this);
...
}
publicvoidactionPerformed(ActionEvente){
....
if(e.getSource()==btn){
}
}
}
Java事件处理示例:
importjavax.swing.*;
importjava.awt.*;
importjava.awt.event.*;
publicclassMyFrmextendsJFrameimplementsActionListener{
/*界面中需要的组件作为属性声明*/
JTextFieldtxt=newJTextField(10);
JLabellbl=newJLabel("姓名");
JButtonbtn=newJButton("查询");
/*组件在构造函数中放置在窗体JFrame上*/
publicMyFrm(){
/*获取JFrame的内容面板ContentPane,控件放在该面板上*/
JPaneljp=(JPanel)this.getContentPane();
/*设置面板布局Layout,如何放?
*/
jp.setLayout(newFlowLayout());
jp.add(lbl);
jp.add(txt);
jp.add(btn);
/*为事件源加一个侦听者*/
btn.addActionListener(this);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
/*事件处理方法*/
publicvoidactionPerformed(ActionEvente){
JOptionPane.showMessageDialog(this,"btn点击");
}
publicstaticvoidmain(Stringarg[]){
JFrame.setDefaultLookAndFeelDecorated(true);//设置纯Java样式
MyFrmfrm=newMyFrm();
frm.setSize(400,300);
frm.setVisible(true);
}
}
注意:
在做下列题目前仔细阅读第一个示例,彻底弄懂Swing界面设计
§5.4实践编程
1、调试运行Swing示例
2、调试运行Java事件处理示例
3、依据题1、2,编写如下界面
当用户点击”ClickMe”按钮,显示消息对话框,消息为”ClickMe按钮被点击”。
packageEx5_3;
importjavax.swing.*;
importjava.awt.*;
importjava.awt.event.*;
publicclassMyFrmextendsJFrameimplementsActionListener{
JButtonbtn=newJButton("ClickMe");
publicMyFrm(){
JPaneljp=(JPanel)this.getContentPane();
jp.setLayout(newFlowLayout());
jp.add(btn);
btn.addActionListener(this);
this.setTitle("ActionEvent");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
publicvoidactionPerformed(ActionEvente){
JOptionPane.showMessageDialog(this,"ClickMe按钮被点击");
}
}
packageEx5_3;
importjavax.swing.*;
importjava.awt.*;
importjava.awt.event.*;
publicclassTest{
publicstaticvoidmain(String[]args){
MyFrmfrm=newMyFrm();
frm.setSize(400,300);
frm.setVisible(true);
}
}
4、编写一个程序实现用户登录界面
当用户登录按下确定键,判断用户是否录入了用户名与密码,如果没有按或用户名不为admin密码不为1234都需要提示错误。
packageEx5_4;
importjavax.swing.*;
importjava.awt.*;
importjava.awt.event.*;
publicclassMyFrmextendsJFrameimplementsActionListener{
JLabellbl_name=newJLabel("用户名");
JLabellbl_pwd=newJLabel("密码");
JTextFieldtxt_name=newJTextField();
JPasswordFieldtxt_pwd=newJPasswordField();
JButtonbtn_OK=newJButton("登陆");
JButtonbtn_Cancel=newJButton("取消");
publicMyFrm(){
JPaneljp=(JPanel)this.getContentPane();
jp.setLayout(newGridLayout(3,2,10,5));
jp.add(lbl_name);jp.add(txt_name);
jp.add(lbl_pwd);jp.add(txt_pwd);
jp.add(btn_OK);jp.add(btn_Cancel);
this.setTitle("登陆");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
btn_OK.addActionListener(this);
}
publicvoidactionPerformed(ActionEvente){
Stringuname=txt_name.getText();
Stringupwd=txt_pwd.getText();
if(uname.equals("")||upwd.equals(""))
JOptionPane.showMessageDialog(this,"用户名或密码未输入!
");
elseif(!
uname.equals("admin")||!
upwd.equals("1234"))
JOptionPane.showMessageDialog(this,"用户名或密码输入错误!
");
elseJOptionPane.showMessageDialog(this,"用户名或密码输入正确!
");
}
}
packageEx5_4;
importjavax.swing.*;
importjava.awt.*;
importjava.awt.event.*;
publicclassTest{
publicstaticvoidmain(String[]args){
JFrame.setDefaultLookAndFeelDecorated(true);
MyFrmfrm=newMyFrm();
frm.setSize(400,200);
frm.setVisible(true);
}
}
5、利用合适的布局和Swing控件完成下题
按照界面使用相应控件与合适的布局完成下题,要求按生成随机数按纽产生三个随机整数0到100之间,按计算平均数按纽计算平均值,如图所示,初始界面
参考:
intx=(Math.random()*41+60);产生随机数
txt1.setText(x+””);将随机数赋予文本框txt1
packageEx5_5;
importjavax.swing.*;
importjava.awt.*;
importjava.awt.event.*;
publicclassMyFrmextendsJFrameimplementsActionListener{
JLabellbl=newJLabel("随机数字一");
JLabellb2=newJLabel("随机数字二");
JLabellb3=newJLabel("随机数字三");
JLabellb4=newJLabel("三数平均值");
JTextFieldtxt1=newJTextField();
JTextFieldtxt2=newJTextField();
JTextFieldtxt3=newJTextField();
JTextFieldtxt4=newJTextField();
JButtonbtn_start=newJButton("生成随机数");
JButtonbtn_average=newJButton("计算平均数");
publicMyFrm(){
JPaneljp=(JPanel)this.getContentPane();
jp.setLayout(newGridLayout(5,2,10,5));
jp.add(lbl);jp.add(txt1);
jp.add(lb2);jp.add(txt2);
jp.add(lb3);jp.add(txt3);
jp.add(lb4);jp.add(txt4);
jp.add(btn_start);jp.add(btn_average);
this.setTitle("三个随机数字");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
btn_start.addActionListener(this);
btn_average.addActionListener(this);
}
publicvoidactionPerformed(ActionEvente){
if(e.getSource()==btn_start){
intx=(int)(Math.random()*41+60);
txt1.setText(x+"");
inty=(int)(Math.random()*41+60);
txt2.setText(y+"");
intz=(int)(Math.random()*41+60);
txt3.setText(z+"");
}
if(e.getSource()==btn_average){
doublex=Double.valueOf(txt1.getText());
doubley=Double.valueOf(txt2.getText());
doublez=Double.valueOf(txt3.getText());
doublet=(x+y+z)/3;
txt4.setText(t+"");
}
}
}
packageEx5_5;
importjavax.swing.*;
importjava.awt.*;
importjava.awt.event.*;
publicclassTest{
publicstaticvoidmain(String[]args){
MyFrmfrm=newMyFrm();
frm.setSize(400,200);
frm.setVisible(true);
}
}
6.编写程序实现如下界面,实现事件如果按下座位i就在控制台中显示“座位i被选中”例如按下“座位0“,则输出座位0被选中”
packageEx5_6;
importjavax.swing.*;
importjava.awt.*;
importjava.awt.event.*;
publicclassMyFrmextendsJFrameimplementsActionListener{
JButtonbtn0=newJButton("讲台");
JButtonbtn1=newJButton("座位1");
JButtonbtn2=newJButton("座位2");
JButtonbtn3=newJButton("座位3");
JButtonbtn4=newJButton("座位4");
JButtonbtn5=newJButton("座位5");
JButtonbtn6=newJButton("座位6");
publicMyFrm(){
JPaneljp=(JPanel)this.getContentPane();
JPaneljp1=newJPanel();
jp1.setLayout(newGridLayout());
jp1.add(btn0);
jp.add(jp1,BorderLayout.NORTH);
JPaneljp2=newJPanel();
jp2.setLayout(newGridLayout(2,3));
jp2.add(btn1);jp2.add(btn2);jp2.add(btn3);
jp2.add(btn4);jp2.add(btn5);jp2.add(btn6);
jp.add(jp2,BorderLayout.CENTER);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
btn1.addActionListener(this);
btn2.addActionListener(this);
btn3.addActionListener(this);
btn4.addActionListener(this);
btn5.addActionListener(this);
btn6.addActionListener(this);
}
publicvoidactionPerformed(ActionEvente){
if(e.getSource()==btn1)
System.out.println("座位1被选中");
if(e.getSource()==btn2)
System.out.println("座位2被选中");
if(e.getSource()==btn3)
Syste