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  <title>NetBeans Property Editor API Tutorial for NetBeans Platform 6.5</title>
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<h1>NetBeans Property Editor Tutorial</h1>
    
<p>This tutorial shows techniques for using property editors in 
NetBeans, including providing custom editors and custom inplace editors. Specifically,
the following will be covered:

<ul>
    <li>Providing your own property editor for an individual Node</li>
    <li>Creating a custom editor</li>
    <li>Creating a custom inplace editor</li>
    <li>Registering a custom property editor globally</li>
</ul>
   <p><b>Contents</b></p>
   
   <img  src="../images/articles/68/netbeans-stamp-65-67-68.gif" class="stamp" width="114" height="114" alt="Content on this page applies to NetBeans IDE 6.5, 6.7, 6.8" title="Content on this page applies to NetBeans IDE 6.5, 6.7, 6.8"> </p>
      <ul class="toc">
            <li><a href="#custom-editors">Introduction to Custom Property Editors</a></li>
            <li><a href="#creating-custom-editor">Creating a Property Editor</a></li>
            <li><a href="#customEditor">Creating a Custom Editor</a></li>
            <li><a href="#inplace-editor">Creating a Custom Inplace Editor</a></li>
            <li><a href="#registering">Registering DatePropertyEditor Globally</a></li>
            <li><a href="#propertypanel">Using PropertyPanel</a></li>
       </ul>
         
<p><b>To follow this tutorial, you need the software and resources listed in the following 
table.</b></p>

       <table>
        <tbody>
            <tr>
                <th class="tblheader" scope="col">Software or Resource</th>
                <th class="tblheader" scope="col">Version Required</th>
            </tr>
            <tr>
                <td class="tbltd1"><a href="https://netbeans.org/downloads/index.html">NetBeans IDE</a></td>
                <td class="tbltd1">version 6.5 or above</td>
            </tr>
            <tr>
                <td class="tbltd1"><a href="http://java.sun.com/javase/downloads/index.jsp">Java Developer Kit (JDK)</a></td>
                <td class="tbltd1">Version 6 or<br/>version 5</td>
            </tr>
        </tbody>
    </table>
  
  <p class="tips">Optionally, for troubleshooting purposes, you
  can <a href="http://plugins.netbeans.org/PluginPortal/faces/PluginDetailPage.jsp?pluginid=3146">download the completed sample</a>.

<!-- ===================================================================================== -->
<h2><a name="custom-editors"></a>Introduction to Custom Property Editors</h2>
<p>Often you may have a property for which either the standard property editor is not
    sufficient, or the property type is a class for which there is no standard 
    property editor.  NetBeans IDE contains classes for many common Swing 
    types, but every possible need cannot be covered by a set of generic property
editors.</p>


<p>This tutorial is intended as a follow-on to these preceding tutorials, and its
code is based on the code from them:
<ul>
    <li><a href="nbm-selection-1.html">Selection Management Tutorial I&#8212;Using a TopComponent's Lookup</a></li>
    <li><a href="nbm-selection-2.html">NetBeans Selection Management Tutorial II&#8212;Using Nodes</a></li>
    <li><a href="nbm-nodesapi2.html">Using the Nodes API</a></li>
</ul>

<p>
You'll pick up where you left off in the previous tutorial, with the class <code>MyNode</code>,
which wraps an <code>APIObject</code> object, and offers a read-only property for 
its <code>index</code> property and a read/write one for its <code>date</code>
property.
<p>

<h2><a name="creating-custom-editor"></a>Creating a Property Editor</h2>
<p>The basics of creating a property editor are pretty simple.  The JavaBeans API
    offers a base class, <code>PropertyEditorSupport</code>, which covers most of 
the basics, and can be used to create a simple property editor with little work.</p>

<p>Property editors serve two purposes:  Converting values to and from strings
for display in the property sheet, and validating new values when they are set.
To start out, you will create a property editor which simply provides and accepts a differently
formatted date.

<ol>
    <li>Right click the <code>org.myorg.myeditor</code> package, and choose 
    New &gt; Java Class.  In the wizard, name the class <code>DatePropertyEditor</code>.</li>
    <li>In the code editor, change the class signature to extend 
    <code>PropertyEditorSupport</code>:
    <pre class=examplecode>
public class DatePropertyEditor extends PropertyEditorSupport {
    </pre>
    </li>
    <li>Implement <code>setAsText()</code> and <code>getAsText()</code> as follows:
    <pre class=examplecode>
public String getAsText() {
    Date d = (Date) getValue();
    if (d == null) {
        return "No Date Set";
    }
    return new SimpleDateFormat("MM/dd/yy HH:mm:ss").format(d);
}

public void setAsText(String s) {
    try {
        setValue (new SimpleDateFormat("MM/dd/yy HH:mm:ss").parse(s));
    } catch (ParseException pe) {
        IllegalArgumentException iae = new IllegalArgumentException ("Could not parse date");
        throw iae;
    }
}
    </pre>
    </li>
    <li>Open <code>MyNode</code> in the code editor.  Change the line that
    declares <code>dateProperty</code> so that the variable is declared as
    <code>PropertySupport.Reflection</code> rather than <code>Property</code>.
    You will be calling a method specific to <code>PropertySupport.Reflection</code>:
    <pre class=examplecode>
PropertySupport.Reflection dateProp = new PropertySupport.Reflection(obj, Date.class, "date");
    </pre>
    </li>
    <li>Insert a new line after that line:
    <pre class=examplecode>
dateProp.setPropertyEditorClass(DatePropertyEditor.class);
    </pre>
    </li>
    <li>Run the module suite, use File &gt; Open Editor to open your editor
    component, and note the new format of the Date property, as shown here:</p>
 <img border="1" border="1" src="../images/tutorials/custom-editors/changed-date-60.png"/>

</li>
</ol>

<h2><a name="customEditor"></a>Creating a Custom Editor</h2>
<p>Another basic feature of standard <code>java.beans.PropertyEditor</code>s is 
    the ability to have a &quot;custom editor&quot;, which usually appears in a 
    dialog when you click a &quot;...&quot; button beside the property in the 
property sheet.</p>

<p>Going into the details of implementing such an editor is out of scope for
this tutorial, but here are the basics:</p>

<ol>
    <li>Implement the following two methods on <code>DatePropertyEditor</code>:
    <pre class=examplecode>
public Component getCustomEditor() {
    return new JLabel ("I want to be a custom editor");
}

public boolean supportsCustomEditor() {
    return true;
}
    </pre>
    </li>
    <li>Run the suite, and now you have a &quot;...&quot; button beside the
    property in the property sheet, as shown below:</p>
<img border="1" border="1" src="../images/tutorials/custom-editors/custom-editor-60-1.png"/> 
<p><p>Click it, and your JLabel appears:</p>
<img border="1" border="1" src="../images/tutorials/custom-editors/custom-editor-60-2.png"/> 
   
<p><p>If you were doing this for real, you would create a JPanel, and embed some
    sort of calendar and/or clock component to make it easy to set the 
properties;  the code necessary to do it right would be a distraction here.</p>

<li>Remove the above two methods before continuing.

</ol>

<h2><a name="inplace-editor"></a>Creating a Custom Inplace Editor</h2>
<p>What would be really useful is to have a better date editor embedded in the
    property sheet itself.  NetBeans has an API that makes this possible.  It 
involves a bit of code, but the result is worth it.</p>
<p>
Since the <a href="https://swingx.dev.java.net/">SwingLabs</a> project on 
java.net produces a nice date picker component, you will simply reuse that.
So the first thing you need to do is to get SwingX into NetBeans.

<ol>
    <li>Download <code>swingx.jar</code> from the 
    <a href="http://swinglabs.org/downloads.jsp">the SwingLabs site</a> (for licensing
    reasons it cannot be kept in NetBeans CVS).</li>
    <li>Expand the SelectionSuite, right-click the Modules node, and choose Add New Library,
    as shown here:</p>
    <p>
    <img border="1" border="1" src="../images/tutorials/custom-editors/library-wrapper-60.png"/>
    </li>
    <li>Browse for <code>swingx.jar</code>, which you just downloaded. Click Next.</li>
    <li>Click Next again, notice that the code name base will be <tt>org.jdesktop.swingx</tt>,
    and then click Finish.</li>
    <li>Right click the My Editor project node in the Projects tab in the 
    main window, and choose Properties.</li>
    <li>In the Libraries page, click the Add Dependency button, and add a dependency
    on your new swingx-wrapper library wrapper module.</li>
</ol>

<p>Now you are ready to make use of the date picker.  This will involve implementing
a couple of NetBeans-specific interfaces:</p>
<ul>
    <li>ExPropertyEditor&#8212;a property editor interface through which the 
    property sheet can pass an &quot;environment&quot; (<code>PropertyEnv</code>)
    object that gives the editor access to the <code>Property</code> object it
    is editing and more.</li>
    <li>InplaceEditor.Factory&#8212;an interface for objects that own an 
    <code>InplaceEditor</code></li>
    <li>InplaceEditor&#8212;an interface that allows a custom component to be
    provided for display in the property sheet.</li>
</ul>

<p>You will implement <code>InplaceEditor.Factory</code> and <code>ExPropertyEditor</code>
directly on <code>DatePropertyEditor</code>, and then create an <code>InplaceEditor</code>
nested class:

<ol>
    <li>Change the signature of <code>DatePropertyEditor</code> as follows:
    <pre class=examplecode>
public class DatePropertyEditor extends PropertyEditorSupport implements ExPropertyEditor, InplaceEditor.Factory {
    </pre>
    </li>
    <li>As in earlier examples, press Ctrl-Shift-I to Fix Imports and then
    use the &quot;Implement All Abstract Methods&quot; to cause the missing methods to
    be added.<p></li>
    <li>Add the following methods to <code>DatePropertyEditor</code>:
    <pre class=examplecode>
public void attachEnv(PropertyEnv env) {
    env.registerInplaceEditorFactory(this);
}

private InplaceEditor ed = null;

public InplaceEditor getInplaceEditor() {
    if (ed == null) {
        ed = new Inplace();
    }
    return ed;
}
    </pre>
    </li>
    <li>Now you need to implement the <code>InplaceEditor</code> itself.  This will be 
    an object that owns a swingx <code>JXDatePicker</code> component, and some
    plumbing methods to set up its value, and dispose of resources when it is no 
    longer in use.
    It requires a bit of code, but it's all quite straightforward.  Just 
    create <code>Inplace</code> as
    a static nested class inside <code>DatePropertyEditor</code>:
    <pre class=examplecode>

    private static class Inplace implements InplaceEditor {
    
        private final JXDatePicker picker = new JXDatePicker();
        private PropertyEditor editor = null;
        
        public void connect(PropertyEditor propertyEditor, PropertyEnv env) {
            editor = propertyEditor;
            reset();
        }

        public JComponent getComponent() {
            return picker;
        }

        public void clear() {
            //avoid memory leaks:
            editor = null;
            model = null;
        }

        public Object getValue() {
            return picker.getDate();
        }

        public void setValue(Object object) {
            picker.setDate ((Date) object);
        }

        public boolean supportsTextEntry() {
            return true;
        }

        public void reset() {
            Date d = (Date) editor.getValue();
            if (d != null) {
                picker.setDate(d);
            }
        }

        public KeyStroke[] getKeyStrokes() {
            return new KeyStroke[0];
        }

        public PropertyEditor getPropertyEditor() {
            return editor;
        }

        public PropertyModel getPropertyModel() {
            return model;
        }

        private PropertyModel model;
        public void setPropertyModel(PropertyModel propertyModel) {
            this.model = propertyModel;
        }

        public boolean isKnownComponent(Component component) {
            return component == picker || picker.isAncestorOf(component);
        }

        public void addActionListener(ActionListener actionListener) {
           //do nothing - not needed for this component
        }

        public void removeActionListener(ActionListener actionListener) {
           //do nothing - not needed for this component
        }
    }
    </pre>
    </li>
    <li>If you haven't already, press Ctrl-Shift-I to Fix Imports.<p></li>
    <li>Run the suite again, use File &gt; Open Editor to open your
        editor (really it's not much of an editor anymore), select an instance
        of <code>MyNode</code> and click the value of the date property in
        the property sheet.  Notice that the date picker popup appears, and
    behaves exactly as it should, as shown below:</p>

    <p>
    <img border="1" src="../images/tutorials/custom-editors/custom-inplace-editor-60.png"/>
</li>
    </ol>


<h2><a name="registering"></a>Registering DatePropertyEditor Globally</h2>
<p>Often it is useful to register a property editor to be used for all properties
    of a given type.  Indeed, your <code>DatePropertyEditor</code> is generally
    useful for any property of the type <code>java.util.Date</code>.  While usefulness
    is not the primary determinant of whether such a property editor should be 
    registered, if your application or module will regularly deal with Date properties,
it might be useful to do so.</p>
<p>Here is how to register <code>DatePropertyEditor</code>
    so that any property of the type <code>java.util.Date</code> will use <code>DatePropertyEditor</code>
in the property sheet:</p>

<ol>
    <li>Right click the My Editor project, and choose Properties
    from the popup menu.
    <p></li>
    <li>On the Libraries page of the project properties dialog, click Add Dependency&#8212;you
    need to add a dependency on the Module System API so you can subclass <code>ModuleInstall</code>
    to run some code on startup.Type <code>ModuleInstall</code>.  The
    dialog should auto-select &quot;Module System API&quot;.  Press Enter or click OK
    to add the dependency on the Modules API from the My Editor module.
    <p></li>
    <li>Right click the <code>org.myorg.myeditor</code> package in the My Editor
    project and choose New &gt; Other.  Under the NetBeans Module Development
    category, select Module Installer. Click Finish.  A
    subclass of <code>org.openide.modules.ModuleInstall</code> will be created for
    you&#8212;this class contains code that will run during startup.
    <p></li>
    <li>Implement the <code>restored()</code> method, which is run during startup,
    as follows:
    <pre class=examplecode>
public void restored() {
    PropertyEditorManager.registerEditor(Date.class, DatePropertyEditor.class);
}
    </pre>
    This code will register <code>DatePropertyEditor</code> as the default editor
    for all properties of the type <code>java.util.Date</code> throughout the system.
    <p></li>
    <li>Press Ctrl-Shift-I to Fix Imports.</li>
</ol>    

<p>Remember, you should only do this if you really need to&#8212;<code>ModuleInstall</code>
    classes slow down application startup, because they mean more code has to run
    during startup.  So where possible they should be avoided.  If you do need to 
    register a lot of property editors, though, it may make sense to aggregate them
in a single module that registers them during startup.</p>  
<p>
<p>If the type you want to provide a property editor for is in your module, it may
    be preferable to place the registration code in a static block that will be 
invoked when that class is loaded, e.g.</p>
<pre class=examplecode>
public class Foo {
    static {
         PropertyEditorManager.registerEditor(Foo.class, FooEditor.class);
    }
    //...
</pre>
<blockquote>
<p><font color="red"><b>Caveat:</b> If you are not sure your property editor
will be used during a typical session, a better technique may be to use 
<code>PropertyEditorManager.setEditorSearchPath()</code>, adding your package
to the array of packages returned by 
<code>PropertyEditorManager.getEditorSearchPath()</code>.  The above code will
cause <code>FooEditor.class</code> to be loaded into memory&#8212;this is paying
a price of about 1K of memory for something that will not be used.  For one
or two property editors, this is probably acceptable;  for more, it is preferable
to aggregate all of your property editors into one package, name the classes
appropriately and register that package is being on the search path.  For 
more information on registering property editors, see the javadoc for 
<code><a href="http://java.sun.com/j2se/1.4.2/docs/api/java/beans/PropertyEditorManager.html">PropertyEditorManager</a></code>.

</font>
</blockquote>


<h2><a name="propertypanel"></a>Using PropertyPanel</h2>
While you won't cover it in great detail, it is worth mentioning that the property
sheet is not the only place that <code>Node.Property</code> objects are useful;
there is also a convenient UI class in the <code>org.openide.explorer.PropertySheet</code>
class called <code>PropertyPanel</code>.  It's function is to display one property,
much as it is displayed in the property sheet, providing an editor field and a
custom editor button, or you have called 
<code>somePropertyPanel.setPreferences(PropertyPanel.PREF_CUSTOM_EDITOR)</code>,
it will display the custom editor for a <code>Property</code>.  It is useful as
a convenient way to get an appropriate UI component for editing any getter/setter
pair for which there is a property editor.

<!--
<h2><a name="propertypanel"></a>Using PropertyPanel</h2>
The property sheet is not the only place <code>Node.Property</code>s are 
useful:  There is also a convenient UI class in the <code>org.openide.explorer.PropertySheet</code>
class called <code>PropertyPanel</code>.  It's function is to display one property,
much as it is displayed in the property sheet, providing an editor field and a
custom editor button.  So for the final exercise, you will modify the <code>MyViewer</code>
component (which is now nearly superfluous, since the property sheet now does
everything it did) to use <code>PropertyPanel</code> to show one property of
the currently selected <code>MyNode</code>.

<ol>
    <li>Right-click the My Viewer project and choose Properties from the popup
    menu</li>
    <li>On the Libraries page, click the Add button.  In the resulting dialog,
    type PropertyPanel.  The dialog should auto-select &quot;Explorer and Property Sheet API&quot;.
    When it does, press Enter or click OK to add the dependency.  The My Viewer
    module can now refer to classes in the property sheet API.
    </li>
    <li>Click the Add button once more, and type &quot;AbstractNode&quot; and
    add a dependency on the Nodes API from My Viewer&#8212;you will be needing 
    that momentarily</li>
    <li>Open <code>MyViewerTopComponent</code> in Matisse, the form editor.</li>
    <li>Select all of the components in <code>MyViewerTopComponent</code> and 
    delete them</li>
    <li>In the Component Inspector, right-click the node labeled &quot;TopComponent&quot;
    and choose Set Layout &gt; FlowLayout from the popup menu.</li>
    <li>Press the Code button in the editor toolbar to switch to the code editor</li>
    <li>Add the following line to the head of the class definition, so it appears thusly:
    <pre class=examplecode>
public final class MyViewerTopComponent extends TopComponent implements LookupListener {
    private final PropertyPanel pnl;
    </pre>
    </li>
    <li>Add the following line at the end of the constructor:
    <pre class=examplecode>
        add (pnl = new PropertyPanel());
    </pre>
    </li>
    -->
</ol>

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