jtextfieldtest.java

详细讲解了java的基础知识

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JTextFieldTest extends JApplet
{

JLabel jLabel1=new JLabel("帐号",JLabel.CENTER);
JLabel jLabel2=new JLabel("密码",JLabel.CENTER);
JLabel jLabel3=new JLabel("有效日期",JLabel.CENTER);
JTextField jTextField1=new JTextField(50);
JPasswordField jPasswordField1=new JPasswordField();
JTextField jTextField3=new JTextField(50);
JPanel jPanel1=new JPanel();
JButton jButton1=new JButton("确定");
JButton jButton2=new JButton("取消");
JPanel jPanel2=new JPanel();

public void init(){
	 jTextField1.setColumns(30);
	 jTextField1.setHorizontalAlignment(  JTextField.CENTER);	 
	 jPanel1.setLayout(new GridLayout(3,2,5,5));	
	 jPanel1.add(jLabel1);
	 jPanel1.add(jTextField1);
		
	 Font ft=new Font("宋体",Font.PLAIN,24);
	 jTextField1.setFont(ft); 
	 jPasswordField1.setFont(ft);
	 jTextField3.setFont(ft);
		
	 jPanel1.add(jLabel2);
	 jPanel1.add(jPasswordField1);
	 jPanel1.add(jLabel3);
	 jPanel1.add(jTextField3);	 
	 this.getContentPane().add(jPanel1,BorderLayout.CENTER);
		
	 jPanel2.add(jButton1);
	 jPanel2.add(jButton2);
	 jPanel2.setLayout(new FlowLayout(FlowLayout.CENTER,5,5));
	 this.getContentPane().add(jPanel2,BorderLayout.SOUTH);
	 this.resize(300,150);
		
	 jButton1.addActionListener(new java.awt.event.ActionListener() {
          public void actionPerformed(ActionEvent e) {
          char[] password=jPasswordField1.getPassword();
		if(password.length<6){//密码长度小于6时作错误信息处理
		JOptionPane.showMessageDialog(jButton1, 
		"密码长度最少需6位数", 		
		"密码错误信息", JOptionPane.ERROR_MESSAGE);
		}
        	    }
       	});	
	
	}

}