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            <div id=PageTitle>How to Use Buttons, Check Boxes, and Radio Buttons</div>
            <blockquote>

<p>
To create a button,
you can instantiate one of the many classes that descend from the
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/AbstractButton.html"><code>AbstractButton</code></a> class.
The following table shows the Swing-defined
<code>AbstractButton</code> subclasses
that you might want to use:

<p>

<table border=0 cellspacing=5>
<tr>
<th align=left >Class<th align=left >Summary<th align=left >Where Described

</th>
</tr>
<tr valign=top>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JButton.html"><code>JButton</code></a></td>
<td> A common button.
</td>
<td> <a href="#abstractbutton">How to Use the Common Button API</a> and
     <a href="#jbutton">How to Use JButton Features</a>

</td>
</tr>
<tr valign=top>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JCheckBox.html"><code>JCheckBox</code></a></td>
<td> A check box button.
</td>
<td> <a href="#checkbox">How to Use Check Boxes</a>

</td>
</tr>
<tr valign=top>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JRadioButton.html"><code>JRadioButton</code></a></td>
<td> One of a group of radio buttons.
</td>
<td> <a href="#radiobutton">How to Use Radio Buttons</a>

</td>
</tr>
<tr valign=top>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JMenuItem.html"><code>JMenuItem</code></a></td>
<td> An item in a menu.
</td>
<td> <a href="menu.html">How to Use Menus</a>

</td>
</tr>
<tr valign=top>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JCheckBoxMenuItem.html"><code>JCheckBoxMenuItem</code></a></td>
<td> A menu item that has a check box.
</td>
<td> <a href="menu.html">How to Use Menus</a>
     and <a href="#checkbox">How to Use Check Boxes</a>

</td>
</tr>
<tr valign=top>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JRadioButtonMenuItem.html"><code>JRadioButtonMenuItem</code></a></td>
<td> A menu item that has a radio button.
</td>
<td> <a href="menu.html">How to Use Menus</a>
     and <a href="#radiobutton">How to Use Radio Buttons</a>

</td>
</tr>
<tr valign=top>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JToggleButton.html"><code>JToggleButton</code></a></td>
<td> Implements toggle functionality
     inherited by 
     <code>JCheckBox</code> and 
     <code>JRadioButton</code>.
     Can be instantiated or subclassed
     to create two-state buttons.
</td>
<td> Used in some
     <a href="#tbeg">examples</a>
</td>
</tr>
</table>

<blockquote><hr><strong>Note:</strong>&nbsp;If you want to collect a group of buttons into a row or column,
then you should check out
<a href="toolbar.html">tool bars</a>.
<hr></blockquote>

First, this section explains the basic button API
that <code>AbstractButton</code> defines &#151;
and thus all Swing buttons have in common.
Next, it describes the small amount of API that
<code>JButton</code> adds to <code>AbstractButton</code>.
After that, this section shows you how to use specialized API
to implement check boxes and radio buttons.

</blockquote>
<h3>
<a name="abstractbutton">How to Use the Common Button API</a>
</h3>
<blockquote>

Here is a picture of an application that displays three buttons:

<p><center><IMG SRC="../../figures/uiswing/components/ButtonDemoMetal.png" WIDTH="489" HEIGHT="96" ALIGN="BOTTOM" ALT="A snapshot of ButtonDemo"></center></p>
<p>


<blockquote><hr><strong>Try this:</strong>&nbsp;
<ol>
<li> <a href="http://java.sun.com/docs/books/tutorialJWS/uiswing/components/examples/ButtonDemo.jnlp">Run ButtonDemo</a> (it requires release 6) using
<a class="TutorialLink" target="_top" href="../../information/javawebstart.html">Java<sup><font size=-2>TM</font></sup> Web Start</a>.    Or, to compile and run the example yourself,
     consult the 
     <a href="examples/index.html#ButtonDemo">example index</a>.
<li> Click the left button.
     <br>
     It disables the middle button
     (and itself, since it's no longer useful)
     and enables the right button.
<li> Click the right button.
     <br>
     It enables the middle button
     and the left button,
     and disables itself.
</ol>
<hr></blockquote>

<p>

As the <code>ButtonDemo</code> example shows,
a Swing button can display both text and an image.
In <code>ButtonDemo</code>,
each button has its text in a different place,
relative to its image.
The underlined letter in each button's text
shows the <em>mnemonic</em> &#151; the keyboard alternative &#151;
for each button.
In most look and feels,
the user can click a button by pressing the Alt key and the mnemonic.
For example, Alt-M would click the Middle button in ButtonDemo.

<p>

When a button is disabled,
the look and feel automatically generates
the button's disabled appearance.
However, you could provide an image to be substituted for the normal image.
For example, you could provide 
gray versions of the images used in the left and right buttons.

<p>

How you implement event handling 
depends on the type of button you use 
and how you use it.
Generally, you implement an 
<a class="TutorialLink" target="_top" href="../events/actionlistener.html">action listener</a>,
which is notified every time the user clicks the button.
For <a href="#checkbox">check boxes</a>
you usually use an
<a class="TutorialLink" target="_top" href="../events/itemlistener.html">item listener</a>,
which is notified when the check box is selected or deselected.

<p>

Below is the code from 

<a class="SourceLink" target="_blank" href="examples/ButtonDemo.java"><code>ButtonDemo.java</code></a>
that creates the buttons in the previous example
and reacts to button clicks.
The bold code is the code
that would remain if the buttons had no images.

<p>

<blockquote><pre>
<em>//In initialization code:</em>
    ImageIcon leftButtonIcon = createImageIcon("images/right.gif");
    ImageIcon middleButtonIcon = createImageIcon("images/middle.gif");
    ImageIcon rightButtonIcon = createImageIcon("images/left.gif");

    <b>b1 = new JButton("Disable middle button"</b>, leftButtonIcon<b>);</b>
    b1.setVerticalTextPosition(AbstractButton.CENTER);
    b1.setHorizontalTextPosition(AbstractButton.LEADING); //aka LEFT, for left-to-right locales
    <b>b1.setMnemonic(KeyEvent.VK_D);</b>
    <b>b1.setActionCommand("disable");</b>

    <b>b2 = new JButton("Middle button"</b>, middleButtonIcon<b>);</b>
    b2.setVerticalTextPosition(AbstractButton.BOTTOM);
    b2.setHorizontalTextPosition(AbstractButton.CENTER);
    <b>b2.setMnemonic(KeyEvent.VK_M);</b>

    <b>b3 = new JButton("Enable middle button"</b>, rightButtonIcon<b>);</b>
    //Use the default text position of CENTER, TRAILING (RIGHT).
    <b>b3.setMnemonic(KeyEvent.VK_E);
    b3.setActionCommand("enable");
    b3.setEnabled(false);</b>

    //Listen for actions on buttons 1 and 3.
    <b>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.");</b>
    ...
}

<b>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);
    }
} </b>

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



</blockquote>
<h3>
<a name="jbutton">How to Use JButton Features</a>
</h3>
<blockquote>

Ordinary buttons &#151; 
<code>JButton</code> objects &#151;
have just a bit more functionality
than the <code>AbstractButton</code> class provides:
You can make a <code>JButton</code>
be the default button.

<p>
At most one button in a top-level container
can be the default button.
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.
Here is a picture of a dialog, implemented in the
<a href="examples/index.html#ListDialog">ListDialog</a> example,
in which the <b>Set</b> button
is the default button:

<p><center><IMG SRC="../../figures/uiswing/components/NameChooserMetal.png" WIDTH="278" HEIGHT="191" ALIGN="BOTTOM" ALT="In the Java Look & Feel, the default button has a heavy border"></center></p>
<p>
You set the default button
by invoking the <code>setDefaultButton</code> method
on a top-level container's root pane.
Here is the code that sets up the default button
for the <code>ListDialog</code> example:

<blockquote><pre>
<em>//In the constructor for a JDialog subclass:</em>
getRootPane().setDefaultButton(setButton);
</pre></blockquote>

The exact implementation of the default button feature
depends on the look and feel.
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.
When no button has the focus, 
the button you originally specified
as the default button becomes the default button again.

</blockquote>
<a name="checkbox">
<h3>How to Use Check Boxes</h3>
</a>
<blockquote>
The 
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JCheckBox.html"><code>JCheckBox</code></a> class provides support for check box buttons.
You can also put check boxes in <a href="menu.html">menus</a>,
using the