初学者,一个小程序

Question

import javax.swing.event.*;

Answer 1

不过还是有错,什么原因呢？
Text.java:13: addDocumentListener(javax.swing.event.DocumentListener) in javax.s
wing.text.Document cannot be applied to (TextField1)
                JTextField1.getDocument().addDocumentListener(this);
                                       ^
Text.java:29: cannot resolve symbol
symbol  : method getPassword ()
location: class javax.swing.JTextField
                System.out.println(JPasswordField1.getPassword());
                                                  ^
2 errors

Answer 2

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;class TextField1 extends JTextField implements DocumentListener //////////////////
{
public TextField1()
{
JTextField1=new JTextField("hi",30);
JPasswordField1=new JPasswordField(null,18);
add(JTextField1);
add(JPasswordField1);
JTextField1.getDocument().addDocumentListener(this);
}
public void insertUpdate(DocumentEvent e)
{
showMsg();
}
public void changedUpdate(DocumentEvent e)/////////////////////////////
{
showMsg();
}
public void removeUpdate(DocumentEvent e)
{
}
private void showMsg()
{
System.out.println(JTextField1.getText().trim());
System.out.println(JPasswordField1.getPassword());
}
private  JTextField JTextField1;
private  JPasswordField JPasswordField1;//////////////////////////
}
class TextFrame extends JFrame
{
public TextFrame()
{
setSize(300,200);
setLocation(300,300);
setTitle("文本域");
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
TextField11=new TextField1();
getContentPane().add(TextField11,"South");//////////////////////
}
private TextField1 TextField11;
}
public class Text
{
public static void main(String[] arg)
{
JFrame textFrame1=new TextFrame();
textFrame1.setVisible(true);
}
}
////////////为改的地方

Answer 3

谢谢楼上那位大哥，我修改后的代码如下,不过为什么只能显示出一个文本域，不能显示密码域，为什么？
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
class TextField1 extends JTextField implements DocumentListener
{
public TextField1()
{
JTextField1=new JTextField("hi",5);
JPasswordField1=new JPasswordField(null,5);
add(JTextField1);
add(JPasswordField1);
JTextField1.getDocument().addDocumentListener(this);
}
public void insertUpdate(DocumentEvent e)
{
showMsg();
}
public void changedUpdate(DocumentEvent e)
{
showMsg();
}
public void removeUpdate(DocumentEvent e)
{
}
private void showMsg()
{
System.out.println(JTextField1.getText().trim());
System.out.println(JPasswordField1.getPassword());
}
private  JTextField JTextField1;
private JPasswordField JPasswordField1;
}
class TextFrame extends JFrame
{
public TextFrame()
{
setSize(300,200);
setLocation(300,300);
setTitle("文本域");
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
TextField11=new TextField1();
getContentPane().add(TextField11,"South");
}
private TextField1 TextField11;
}
public class Text
{
public static void main(String[] arg)
{
JFrame textFrame1=new TextFrame();
textFrame1.setVisible(true);
}
}