How to Use Buttons, Check Boxes, and Radio Buttons如何使用按钮、复选框和单选按钮

To create a button, you can instantiate one of the many classes that descend from the AbstractButton class. 要创建按钮，可以实例化从AbstractButton类派生的许多类之一。The following table shows the Swing-defined AbstractButton subclasses that you might want to use:下表显示了您可能希望使用的Swing定义的AbstractButton子类：

First, this section explains the basic button API that AbstractButton defines — and thus all Swing buttons have in common. 首先，本节解释AbstractButton定义的基本按钮API；因此所有摆动按钮具有共同点。Next, it describes the small amount of API that JButton adds to AbstractButton. 接下来，它描述了JButton添加到AbstractButton的少量API。After that, this section shows you how to use specialized API to implement check boxes and radio buttons.之后，本节将向您展示如何使用专门的API来实现复选框和单选按钮。

How to Use the Common Button API如何使用公共按钮API

Here is a picture of an application that displays three buttons:下面是显示三个按钮的应用程序的图片：

As the ButtonDemo example shows, a Swing button can display both text and an image. 如ButtonDemo示例所示，Swing按钮可以同时显示文本和图像。In ButtonDemo, each button has its text in a different place, relative to its image. 在ButtonDemo中，每个按钮的文本相对于其图像位于不同的位置。The underlined letter in each button's text shows the mnemonic — the keyboard alternative — for each button. 每个按钮文本中带下划线的字母显示助记符—键盘替代—对于每个按钮。In most look and feels, the user can click a button by pressing the Alt key and the mnemonic. 在大多数外观中，用户可以通过按Alt键和助记符来单击按钮。For example, Alt-M would click the Middle button in ButtonDemo.例如，Alt-M将单击ButtonDemo中的中间按钮。

When a button is disabled, the look and feel automatically generates the button's disabled appearance. 禁用按钮时，外观将自动生成按钮的禁用外观。However, you could provide an image to be substituted for the normal image. 但是，您可以提供一个图像来替代正常图像。For example, you could provide gray versions of the images used in the left and right buttons.例如，您可以提供左右按钮中使用的图像的灰色版本。

How you implement event handling depends on the type of button you use and how you use it. 如何实现事件处理取决于使用的按钮类型和使用方式。Generally, you implement an action listener, which is notified every time the user clicks the button. 通常，您实现了一个动作监听器，每次用户单击按钮时都会收到通知。For check boxes you usually use an item listener, which is notified when the check box is selected or deselected.对于复选框，您通常使用项目侦听器，当选中或取消选中复选框时，会通知该侦听器。

Below is the code from ButtonDemo.java that creates the buttons in the previous example and reacts to button clicks. 下面是ButtonDemo.java中的代码，它在前面的示例中创建按钮并对按钮单击做出反应。The bold code is the code that would remain if the buttons had no images.粗体代码是在按钮没有图像时保留的代码。

//In initialization code:
    ImageIcon leftButtonIcon = createImageIcon("images/right.gif");
    ImageIcon middleButtonIcon = createImageIcon("images/middle.gif");
    ImageIcon rightButtonIcon = createImageIcon("images/left.gif");
b1 = new JButton("Disable middle button", leftButtonIcon);
    b1.setVerticalTextPosition(AbstractButton.CENTER);
    b1.setHorizontalTextPosition(AbstractButton.LEADING); //aka LEFT, for left-to-right locales
b1.setMnemonic(KeyEvent.VK_D);
b1.setActionCommand("disable");
b2 = new JButton("Middle button", middleButtonIcon);
    b2.setVerticalTextPosition(AbstractButton.BOTTOM);
    b2.setHorizontalTextPosition(AbstractButton.CENTER);
b2.setMnemonic(KeyEvent.VK_M);
b3 = new JButton("Enable middle button", rightButtonIcon);
    //Use the default text position of CENTER, TRAILING (RIGHT).
b3.setMnemonic(KeyEvent.VK_E);
    b3.setActionCommand("enable");
    b3.setEnabled(false);

    //Listen for actions on buttons 1 and 3.
b1.addActionListener(this);
    b3.addActionListener(this);

    b1.setToolTipText("Click this button to disable "
                      + "the middle button.");
    b2.setToolTipText("This middle button does nothing "
                      + "when you click it.");
    b3.setToolTipText("Click this button to enable the "
                      + "middle button.");
    ...
}
public void actionPerformed(ActionEvent e) {
    if ("disable".equals(e.getActionCommand())) {
        b2.setEnabled(false);
        b1.setEnabled(false);
        b3.setEnabled(true);
    } else {
        b2.setEnabled(true);
        b1.setEnabled(true);
        b3.setEnabled(false);
    }
}

protected static ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = ButtonDemo.class.getResource(path);
    ...//error handling omitted for clarity...
    return new ImageIcon(imgURL);
}

How to Use JButton Features如何使用JButton功能

Ordinary buttons — JButton objects — have just a bit more functionality than the AbstractButton class provides: You can make a JButton be the default button.普通按钮—JButton对象—比AbstractButton类提供的功能多一点：您可以将JButton设置为默认按钮。

At most one button in a top-level container can be the default button. 顶级容器中最多有一个按钮可以是默认按钮。The default button typically has a highlighted appearance and acts clicked whenever the top-level container has the keyboard focus and the user presses the Return or Enter key. 默认按钮通常具有突出显示的外观，每当顶级容器具有键盘焦点并且用户按下回车键或回车键时，默认按钮就会被单击。Here is a picture of a dialog, implemented in the ListDialog example, in which the Set button is the default button:下面是在ListDialog示例中实现的对话框的图片，其中设置按钮是默认按钮：

You set the default button by invoking the setDefaultButton method on a top-level container's root pane. 通过在顶级容器的根窗格上调用setDefaultButton方法来设置默认按钮。Here is the code that sets up the default button for the ListDialog example:下面是为ListDialog示例设置默认按钮的代码：

//In the constructor for a JDialog subclass:
getRootPane().setDefaultButton(setButton);

The exact implementation of the default button feature depends on the look and feel. 默认按钮功能的确切实现取决于外观。For example, in the Windows look and feel, the default button changes to whichever button has the focus, so that pressing Enter clicks the focused button. 例如，在Windows look and feel中，默认按钮更改为具有焦点的按钮，因此按Enter键可单击焦点按钮。When no button has the focus, the button you originally specified as the default button becomes the default button again.当没有按钮具有焦点时，最初指定为默认按钮的按钮将再次成为默认按钮。

How to Use Check Boxes如何使用复选框

The JCheckBox class provides support for check box buttons. JCheckBox类提供对复选框按钮的支持。You can also put check boxes in menus, using the JCheckBoxMenuItem class. 您还可以使用JCheckBoxMenuItem类在菜单中放置复选框。Because JCheckBox and JCheckBoxMenuItem inherit from AbstractButton, Swing check boxes have all the usual button characteristics, as discussed earlier in this section. 因为JCheckBox和JCheckBoxMenuItem继承自AbstractButton，所以Swing复选框具有所有常见的按钮特性，如本节前面讨论的。For example, you can specify images to be used in check boxes.例如，可以指定要在复选框中使用的图像。

Check boxes are similar to radio buttons but their selection model is different, by convention. 复选框类似于单选按钮，但按照惯例，它们的选择模式不同。Any number of check boxes in a group — none, some, or all — can be selected. 组中的任意数量的复选框—无、部分或全部—可以选择。A group of radio buttons, on the other hand, can have only one button selected.另一方面，一组单选按钮只能选择一个按钮。

Here is a picture of an application that uses four check boxes to customize a cartoon:以下是使用四个复选框自定义卡通的应用程序的图片：

A check box generates one item event and one action event per click. 复选框每次单击生成一个项目事件和一个操作事件。Usually, you listen only for item events, since they let you determine whether the click selected or deselected the check box. 通常，您只侦听项目事件，因为它们允许您确定单击是选中还是取消选中复选框。Below is the code from CheckBoxDemo.java that creates the check boxes in the previous example and reacts to clicks.下面是CheckBoxDemo.java中的代码，用于创建上一个示例中的复选框并对单击做出反应。

//In initialization code:
    chinButton = new JCheckBox("Chin");
    chinButton.setMnemonic(KeyEvent.VK_C); 
    chinButton.setSelected(true);

    glassesButton = new JCheckBox("Glasses");
    glassesButton.setMnemonic(KeyEvent.VK_G); 
    glassesButton.setSelected(true);

    hairButton = new JCheckBox("Hair");
    hairButton.setMnemonic(KeyEvent.VK_H); 
    hairButton.setSelected(true);

    teethButton = new JCheckBox("Teeth");
    teethButton.setMnemonic(KeyEvent.VK_T); 
    teethButton.setSelected(true);

    //Register a listener for the check boxes.
    chinButton.addItemListener(this);
    glassesButton.addItemListener(this);
    hairButton.addItemListener(this);
    teethButton.addItemListener(this);
...
public void itemStateChanged(ItemEvent e) {
    ...
    Object source = e.getItemSelectable();

    if (source == chinButton) {
        //...make a note of it...
    } else if (source == glassesButton) {
        //...make a note of it...
    } else if (source == hairButton) {
        //...make a note of it...
    } else if (source == teethButton) {
        //...make a note of it...
    }

    if (e.getStateChange() == ItemEvent.DESELECTED)
        //...make a note of it...
    ...
    updatePicture();
}

How to Use Radio Buttons如何使用单选按钮

Radio buttons are groups of buttons in which, by convention, only one button at a time can be selected. 单选按钮是一组按钮，按照惯例，一次只能选择一个按钮。The Swing release supports radio buttons with the JRadioButton and ButtonGroup classes. Swing版本支持带有JRadioButton和ButtonGroup类的单选按钮。To put a radio button in a menu, use the JRadioButtonMenuItem class. 要在菜单中放置单选按钮，请使JRadioButtonMenuItem类。Other ways of displaying one-of-many choices are combo boxes and lists. 显示许多选项之一的其他方式是组合框和列表。Radio buttons look similar to check boxes, but, by convention, check boxes place no limits on how many items can be selected at a time.单选按钮看起来类似于复选框，但按照惯例，复选框对一次可以选择的项目数量没有限制。

Because JRadioButton inherits from AbstractButton, Swing radio buttons have all the usual button characteristics, as discussed earlier in this section. 由于JRadioButton继承自AbstractButton，Swing单选按钮具有所有常见的按钮特性，如本节前面所述。For example, you can specify the image displayed in a radio button.例如，可以指定单选按钮中显示的图像。

Here is a picture of an application that uses five radio buttons to let you choose which kind of pet is displayed:下面是一个应用程序的图片，它使用五个单选按钮让您选择显示哪种宠物：

Each time the user clicks a radio button (even if it was already selected), the button fires an action event. 每次用户单击单选按钮（即使它已被选中），该按钮都会触发一个动作事件。One or two item events also occur — one from the button that was just selected, and another from the button that lost the selection (if any). 还发生一个或两个项目事件；一个来自刚刚选择的按钮，另一个来自丢失选择的按钮（如果有）。Usually, you handle radio button clicks using an action listener.通常，您使用操作侦听器处理单选按钮单击。

Below is the code from RadioButtonDemo.java that creates the radio buttons in the previous example and reacts to clicks.下面是RadioButtonDemo.java中的代码，该代码在前面的示例中创建单选按钮并对单击做出反应。

//In initialization code:
    //Create the radio buttons.
    JRadioButton birdButton = new JRadioButton(birdString);
    birdButton.setMnemonic(KeyEvent.VK_B);
    birdButton.setActionCommand(birdString);
    birdButton.setSelected(true);

    JRadioButton catButton = new JRadioButton(catString);
    catButton.setMnemonic(KeyEvent.VK_C);
    catButton.setActionCommand(catString);

    JRadioButton dogButton = new JRadioButton(dogString);
    dogButton.setMnemonic(KeyEvent.VK_D);
    dogButton.setActionCommand(dogString);

    JRadioButton rabbitButton = new JRadioButton(rabbitString);
    rabbitButton.setMnemonic(KeyEvent.VK_R);
    rabbitButton.setActionCommand(rabbitString);

    JRadioButton pigButton = new JRadioButton(pigString);
    pigButton.setMnemonic(KeyEvent.VK_P);
    pigButton.setActionCommand(pigString);

    //Group the radio buttons.
    ButtonGroup group = new ButtonGroup();
    group.add(birdButton);
    group.add(catButton);
    group.add(dogButton);
    group.add(rabbitButton);
    group.add(pigButton);

    //Register a listener for the radio buttons.
    birdButton.addActionListener(this);
    catButton.addActionListener(this);
    dogButton.addActionListener(this);
    rabbitButton.addActionListener(this);
    pigButton.addActionListener(this);
...
public void actionPerformed(ActionEvent e) {
    picture.setIcon(new ImageIcon("images/" 
                                  + e.getActionCommand() 
                                  + ".gif"));
}

For each group of radio buttons, you need to create a ButtonGroup instance and add each radio button to it. 对于每组单选按钮，您需要创建一个ButtongGroup实例并将每个单选按钮添加到其中。The ButtonGroup takes care of deselecting the previously selected button when the user selects another button in the group.当用户选择组中的另一个按钮时，ButtonGroup负责取消选择先前选择的按钮。

You should generally initialize a group of radio buttons so that one is selected. 通常应初始化一组单选按钮，以便选择一个。However, the API doesn't enforce this rule — a group of radio buttons can have no initial selection. Once the user has made a selection, exactly one button is selected from then on.然而，API不强制执行该规则—一组单选按钮可以没有初始选择。一旦用户做出选择，从那时起只选择一个按钮。

The Button API按钮API

The following tables list the commonly used button-related API. 下表列出了常用的按钮相关API。Other methods you might call, such as setFont and setForeground, are listed in the API tables in The JComponent Class.您可能调用的其他方法，如setFont和setForeground，在JComponent类的API表中列出。

The API for using buttons falls into these categories:使用按钮的API分为以下几类：

• Setting or Getting the Button's Contents设置或获取按钮的内容
• Fine Tuning the Button's Appearance微调按钮的外观
• Implementing the Button's Functionality实现按钮的功能
• Check Box Constructors复选框构造函数
• Radio Button Constructors单选按钮构造函数
• Toggle Button Constructors切换按钮构造函数
• Commonly Used Button Group Constructors/Methods常用按钮组构造函数/方法

Examples that Use Various Kinds of Buttons使用各种按钮的示例

The following examples use buttons. 以下示例使用按钮。Also see Examples that Use Tool Bars, which lists programs that add JButton objects to JToolBars.另请参见使用工具栏的示例，其中列出了将JButton对象添加到JToolbar的程序。

You can learn more about JavaFX button components from the following documents:您可以从以下文档中了解有关JavaFX按钮组件的更多信息：

• Using JavaFX UI Controls: Button使用JavaFXUI控件：按钮
• Using JavaFX UI Controls: Radio Button使用JavaFXUI控件：单选按钮
• Using JavaFX UI Controls: Toggle Button使用JavaFXUI控件：切换按钮
• Using JavaFX UI Controls: Check box使用JavaFX UI控件：复选框