AWT TextField类

介绍

TextField组件允许用户编辑单行文本。当用户在文本字段中键入一个关键的事件被发送到TextField。键盘事件，可能是按下键盘，重点发布或关键的类型。键盘事件被传递到注册keyListener。它也有可能为一个ActionEvent ActionEvent 启用ActionEvent文本框，然后按回车键可能被触发。

类的声明

以下是声明java.awt.TextField类：

public class TextField
   extends TextComponent

类的构造函数

S.N.	构造函数与说明
1	TextField() Constructs a new text field.
2	TextField(int columns) Constructs a new empty text field with the specified number of columns.
3	TextField(String text) Constructs a new text field initialized with the specified text.
4	TextField(String text, int columns) Constructs a new text field initialized with the specified text to be displayed, and wide enough to hold the specified number of columns.

类方法

S.N.	方法和说明
1	void addActionListener(ActionListener l) Adds the specified action listener to receive action events from this text field.
2	void addNotify() Creates the TextField's peer.
3	boolean echoCharIsSet() Indicates whether or not this text field has a character set for echoing.
4	AccessibleContext getAccessibleContext() Gets the AccessibleContext associated with this TextField.
5	ActionListener[] getActionListeners() Returns an array of all the action listeners registered on this textfield.
6	int getColumns() Gets the number of columns in this text field.
7	char getEchoChar() Gets the character that is to be used for echoing.
8	<T extends EventListener> T[] getListeners(Class<T> listenerType) Returns an array of all the objects currently registered as FooListeners upon this TextField.
9	Dimension getMinimumSize() Gets the minumum dimensions for this text field.
10	Dimension getMinimumSize(int columns) Gets the minumum dimensions for a text field with the specified number of columns.
11	Dimension getPreferredSize() Gets the preferred size of this text field.
12	Dimension getPreferredSize(int columns) Gets the preferred size of this text field with the specified number of columns.
13	Dimension minimumSize() Deprecated. As of JDK version 1.1, replaced by getMinimumSize().
14	Dimension minimumSize(int columns) Deprecated. As of JDK version 1.1, replaced by getMinimumSize(int).
15	protected String paramString() Returns a string representing the state of this TextField.
16	Dimension preferredSize() Deprecated. As of JDK version 1.1, replaced by getPreferredSize().
17	Dimension preferredSize(int columns) Deprecated. As of JDK version 1.1, replaced by getPreferredSize(int).
18	protected void processActionEvent(ActionEvent e) Processes action events occurring on this text field by dispatching them to any registered ActionListener objects.
19	protected void processEvent(AWTEvent e) Processes events on this text field.
20	void removeActionListener(ActionListener l) Removes the specified action listener so that it no longer receives action events from this text field.
21	void setColumns(int columns) Sets the number of columns in this text field.
22	void setEchoChar(char c) Sets the echo character for this text field.
23	void setEchoCharacter(char c) Deprecated. As of JDK version 1.1, replaced by setEchoChar(char).
24	void setText(String t) Sets the text that is presented by this text component to be the specified text.

继承的方法

这个类继承的方法从以下类：

java.awt.TextComponent
java.awt.Component
java.lang.Object

TextField 实例

选择使用任何编辑器创建以下java程序 D:/ > AWT > com > yiibai > gui >

AwtControlDemo

package com.yiibai.gui;

import java.awt.*;
import java.awt.event.*;

public class AwtControlDemo {

   private Frame mainFrame;
   private Label headerLabel;
   private Label statusLabel;
   private Panel controlPanel;

   public AwtControlDemo(){
      prepareGUI();
   }

   public static void main(String[] args){
      AwtControlDemo  awtControlDemo = new AwtControlDemo();
      awtControlDemo.showTextFieldDemo();
   }

   private void prepareGUI(){
      mainFrame = new Frame("Java AWT Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      headerLabel = new Label();
      headerLabel.setAlignment(Label.CENTER);
      statusLabel = new Label();        
      statusLabel.setAlignment(Label.CENTER);
      statusLabel.setSize(350,100);

      controlPanel = new Panel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }

   private void showTextFieldDemo(){
      headerLabel.setText("Control in action: TextField"); 

      Label  namelabel= new Label("User ID: ", Label.RIGHT);
      Label  passwordLabel = new Label("Password: ", Label.CENTER);
      final TextField userText = new TextField(6);
      final TextField passwordText = new TextField(6);
      passwordText.setEchoChar('*');

      Button loginButton = new Button("Login");
   
      loginButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {     
            String data = "Username: " + userText.getText();
            data += ", Password: " + passwordText.getText();
            statusLabel.setText(data);        
         }
      }); 

      controlPanel.add(namelabel);
      controlPanel.add(userText);
      controlPanel.add(passwordLabel);       
      controlPanel.add(passwordText);
      controlPanel.add(loginButton);
      mainFrame.setVisible(true);  
   }
}

编译程序，使用命令提示符。到 D:/ > AWT 然后键入以下命令。

D:AWT>javac comyiibaiguiAwtControlDemo.java

如果没有错误出现，这意味着编译成功。使用下面的命令来运行程序。

D:AWT>java com.yiibai.gui.AwtControlDemo

验证下面的输出