AWT CheckBox类 - AWT

介绍

CheckBox控件是用来开启选项（true）或关闭（false）。每个复选框标签代表的复选框做什么。通过点击它可以改变一个复选框的状态。

类的声明

以下是声明的java.awt.Checkbox类：

public class Checkbox
   extends Component
      implements ItemSelectable,Accessible

类的构造函数

S.N.	构造函数与说明
1	Checkbox() Creates a check box with an empty string for its label.
2	Checkbox(String label) Creates a check box with the specified label.
3	Checkbox(String label, boolean state) Creates a check box with the specified label and sets the specified state.
4	Checkbox(String label, boolean state, CheckboxGroup group) Constructs a Checkbox with the specified label, set to the specified state, and in the specified check box group.
5	Checkbox(String label, CheckboxGroup group, boolean state) Creates a check box with the specified label, in the specified check box group, and set to the specified state.

类方法

S.N.	方法和说明
1	void addItemListener(ItemListener l) Adds the specified item listener to receive item events from this check box.
2	void addNotify() Creates the peer of the Checkbox.
3	AccessibleContext getAccessibleContext() Gets the AccessibleContext associated with this Checkbox.
4	CheckboxGroup getCheckboxGroup() Determines this check box's group.
5	ItemListener[] getItemListeners() Returns an array of all the item listeners registered on this checkbox.
6	String getLabel() Gets the label of this check box.
7	<T extends EventListener>T[] getListeners(Class<T> listenerType) Returns an array of all the objects currently registered as FooListeners upon this Checkbox.
8	Object[] getSelectedObjects() Returns an array (length 1) containing the checkbox label or null if the checkbox is not selected.
9	boolean getState() Determines whether this check box is in the on or off state.
10	protected String paramString() Returns a string representing the state of this Checkbox.
11	protected void processEvent(AWTEvent e) Processes events on this check box.
12	protected void processItemEvent(ItemEvent e) Processes item events occurring on this check box by dispatching them to any registered ItemListener objects.
13	void removeItemListener(ItemListener l) Removes the specified item listener so that the item listener no longer receives item events from this check box.
14	void setCheckboxGroup(CheckboxGroup g) Sets this check box's group to the specified check box group.
15	void setLabel(String label) Sets this check box's label to be the string argument.
16	void setState(boolean state) Sets the state of this check box to the specified state.

继承的方法

这个类继承的方法从以下类：

java.awt.Component
java.lang.Object

CheckBox的示例

说在您选择使用的编辑器创建以下java程序 D:/ > AWT > com > yiibai.com > gui >

AwtControlDemo.java

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.showCheckBoxDemo();
   }

   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 showCheckBoxDemo(){

      headerLabel.setText("Control in action: CheckBox"); 

      Checkbox chkApple = new Checkbox("Apple");
      Checkbox chkMango = new Checkbox("Mango");
      Checkbox chkPeer = new Checkbox("Peer");

      chkApple.addItemListener(new ItemListener() {
         public void itemStateChanged(ItemEvent e) {             
            statusLabel.setText("Apple Checkbox: " 
            + (e.getStateChange()==1?"checked":"unchecked"));
         }
      });

      chkMango.addItemListener(new ItemListener() {
         public void itemStateChanged(ItemEvent e) {
            statusLabel.setText("Mango Checkbox: " 
            + (e.getStateChange()==1?"checked":"unchecked"));
         }
      });

      chkPeer.addItemListener(new ItemListener() {
         public void itemStateChanged(ItemEvent e) {
            statusLabel.setText("Peer Checkbox: " 
            + (e.getStateChange()==1?"checked":"unchecked"));
         }
      });

      controlPanel.add(chkApple);
      controlPanel.add(chkMango);
      controlPanel.add(chkPeer);       

      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

AWT CheckBox