JTextFieldDemo(原创)

代码:

package MyJava.Base;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
import java.awt.Toolkit;

class JTextFieldFrame extends JFrame
{ 
 private JLabel lblName=null;
 private JLabel lblSex=null;
 private JLabel lblHeight=null;
 private JLabel lblWeight=null;
 private JLabel lblPwd=null;
 
 private JTextField txtName=null;
 private JTextField txtSex=null;
 private JTextField txtHeight=null;
 private JTextField txtWeight=null;
 private JPasswordField pwd=null;
 
 public JTextFieldFrame(String title)
 { 
  super(title);
  setSize(300,200);
  Container container=this.getContentPane();
  container.setLayout(new BorderLayout());
  
  JPanel pane=new JPanel(new GridBagLayout());
  GridBagConstraints gbc=new GridBagConstraints();
  
  gbc.anchor=GridBagConstraints.WEST;
  gbc.insets=new Insets(2,2,2,2);
  
  pane.setBorder(BorderFactory.createTitledBorder("个人信息"));
  
  lblName=new JLabel("姓名");
  lblSex=new JLabel("性别");
  lblHeight=new JLabel("身高");
  lblWeight=new JLabel("体重");
  lblPwd=new JLabel("密码");
  
  //构造JTextField的几种方式
  //指定初始字段长度
  txtName=new JTextField(new JTextField_Filter(10),"luliuyan",10);
  //建立新的JTextField
  txtSex=new JTextField();
  //指定初始字符串
  txtHeight=new JTextField("173cm");
  //指定初始字符串和初始字段长度
  txtWeight=new JTextField("80kg,有点重了",20);
  
  pwd=new JPasswordField(new JPasswordField_Filter(10),"",10);
  
  //设置字段显示的字符
  pwd.setEchoChar('$');
  
  gbc.gridx=0;
  gbc.gridy=0;
  pane.add(lblName,gbc);
  
  gbc.gridx=1;
  pane.add(txtName,gbc);
  
  gbc.gridx=0;
  gbc.gridy=1;
  pane.add(lblSex,gbc);
  
  gbc.gridx=1;
  pane.add(txtSex,gbc);
  
  gbc.gridx=0;
  gbc.gridy=2;
  pane.add(lblHeight,gbc);
  
  gbc.gridx=1;
  pane.add(txtHeight,gbc);
  
  gbc.gridx=0;
  gbc.gridy=3;
  pane.add(lblWeight,gbc);
  
  gbc.gridx=1;
  pane.add(txtWeight,gbc);
  
  gbc.gridx=0;
  gbc.gridy=4;
  pane.add(lblPwd,gbc);
  
  gbc.gridx=1;
  pane.add(pwd,gbc);
  
  container.add(pane);
  
  
 }
}

class JTextField_Filter extends PlainDocument
{ 
 private int maxLength=0;
 public JTextField_Filter(int max)
 { 
  this.maxLength=max;
 }
 
 public void insertString(int offset,String str,AttributeSet att) throws BadLocationException
 { 
  if(getLength()+str.length()>maxLength)
  { 
   Toolkit.getDefaultToolkit().beep();
  } 
  else
  { 
   super.insertString(offset,str,att); 
  }
 }

}
class JPasswordField_Filter extends PlainDocument
{ 
 private int maxLength=0;
 int result;
 public JPasswordField_Filter(int max)
 { 
  this.maxLength=max;
 }
 
 public void insertString(int offset,String str,AttributeSet att) throws BadLocationException
 { 
  for(int i=0;i<9;i++)
  {
   result=Integer.toString(i).compareTo(str);
   if(result==0)
   {
    if(getLength()+str.length()>maxLength)
    { 
     Toolkit.getDefaultToolkit().beep();
    } 
    else
    { 
     super.insertString(offset,str,att); 
    }
   }
  }
 }
 

}
public class JTextFieldDemo
{ 
 public static void main(String[] args) throws Exception
 { 
  JTextFieldFrame frame=new JTextFieldFrame("JTextFieldDemo");
 
  frame.setVisible(true);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 }
}

 

 

程序运行的结果

 

 

注意姓名字段的长度限制，不能输入大于10个字符的姓名