netbeans.apache.org/src/old_content/content/tutorials/74/nbm-property-editors.adoc

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= NetBeans Property Editor Tutorial
:jbake-type: platform_tutorial
:jbake-tags: tutorials 
:jbake-status: published
:syntax: true
:source-highlighter: pygments
:toc: left
:toc-title:
:icons: font
:experimental:
:description: NetBeans Property Editor Tutorial - Apache NetBeans
:keywords: Apache NetBeans Platform, Platform Tutorials, NetBeans Property Editor Tutorial

This tutorial shows techniques for using property editors in NetBeans, including providing custom editors and custom inplace editors. Specifically, the following will be covered:

* Providing your own property editor for an individual Node
* Creating a custom editor
* Creating a custom inplace editor
* Registering a custom property editor globally

NOTE: This document uses NetBeans Platform 7.3 and NetBeans IDE 7.3. If you are using an earlier version, see  link:72/nbm-nodesapi2.html[the previous version of this document].







For troubleshooting purposes, you are welcome to download the  link:http://web.archive.org/web/20170409072842/http://java.net/projects/nb-api-samples/show/versions/7.3/tutorials/selection-management/4-of-4/EventManager[completed tutorial source code].

Related community tutorials:

*  link:http://netbeans.dzone.com/nb-custom-float-propertyeditor[Custom Float Property Editor (1)]
*  link:http://netbeans.dzone.com/nb-custom-float-propertyeditor-2[Custom Float Property Editor (2)]


== Introduction to Custom Property Editors

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 Java types, but every possible need cannot be covered by a set of generic property editors.

This tutorial is intended as a follow-on to these preceding tutorials, and its code is based on the code from them:

*  link:nbm-selection-1.html[Selection Management Tutorial I—Using a TopComponent's Lookup]
*  link:nbm-selection-2.html[NetBeans Selection Management Tutorial II—Using Nodes]
*  link:nbm-nodesapi2.html[Using the Nodes API]

You'll pick up where you left off in the previous tutorial, with the class `EventNode`, which wraps an `Event` object, and offers a read-only property for its `index` property and a read/write one for its `date` property.


== Creating a Property Editor

The basics of creating a property editor are pretty simple. The JavaBeans API offers a base class, `PropertyEditorSupport`, which covers most of the basics, and can be used to create a simple property editor with little work.

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.


[start=1]
1. Right click the `org.myorg.myeditor` package, and choose New > Java Class. In the wizard, name the class `DatePropertyEditor`.

[start=2]
1. In the code editor, change the class signature to extend `PropertyEditorSupport`:

[source,java]
----

public class DatePropertyEditor extends PropertyEditorSupport {
----


[start=3]
1. Implement `setAsText()` and `getAsText()` as follows:

[source,java]
----

@Override
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);
}

@Override
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;
    }
}
----


[start=4]
1. Open `EventNode` in the code editor. Change the line that declares `dateProperty` so that the variable is declared as `PropertySupport.Reflection` rather than `Property`. You will be calling a method specific to `PropertySupport.Reflection`:

[source,java]
----

PropertySupport.Reflection dateProp = new PropertySupport.Reflection(obj, Date.class, "date");
----


[start=5]
1. Insert a new line after that line:

[source,java]
----

dateProp.setPropertyEditorClass(DatePropertyEditor.class);
----


[start=6]
1. Run the Event Manager and note the new format of the Date property, as shown here:


image::images/property-editors_date-editor-1.png[]


== Creating a Custom Editor

Another basic feature of standard `java.beans.PropertyEditor`s is the ability to have a "custom editor", which usually appears in a dialog when you click a "..." button beside the property in the property sheet.

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


[start=1]
1. Implement the following two methods on `DatePropertyEditor`:

[source,java]
----

@Override
public Component getCustomEditor() {
    return new JLabel ("I want to be a custom editor");
}

@Override
public boolean supportsCustomEditor() {
    return true;
}
                    
----


[start=2]
1. Run the Event Manager, and now you have a "..." button beside the property in the property sheet, as shown below:


image::images/property-editors_date-editor-2.png[]

Click it, and your JLabel appears:


image::images/property-editors_date-editor-3.png[]

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.


[start=3]
1. Remove both of the above two methods before continuing because we're going to create a real date editor in the next section.


== Creating a Custom Inplace Editor

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.

Since the SwingX project includes a nice date picker component, you will simply reuse that. So the first thing you need to do is to get SwingX into the Event Manager. Since NetBeans IDE bundles SwingX, we will use the bundled  ``swingx.jar``  by browsing into the NetBeans IDE installation directory and creating a new module from the swingx.jar that we will find there.


[start=1]
1. Expand the Event Manager, right-click the Modules node, and choose Add New Library, as shown here:


image::images/property-editors_date-editor-4.png[]


[start=2]
1. Browse for `swingx-all-1.6.4.jar` (or whatever version of the JAR is available) in "ide/modules/ext" in the NetBeans IDE installation directory.


image::images/property-editors_date-editor-5.png[]

Click Next.


[start=3]
1. Click Next again without making any changes to the below:


image::images/property-editors_date-editor-6.png[]


[start=4]
1. Set the code name base to  ``org.jdesktop.swingx`` :


image::images/property-editors_date-editor-7.png[]

Click Finish and you should see the new module, wrapping the selected JAR:


image::images/property-editors_date-editor-8.png[]


[start=5]
1. Right click the My Editor project node in the Projects tab in the main window, and choose Properties. In the Libraries page, click the Add Dependency button, and add a dependency on your new "swingx-all" module. When you click OK, you will see the new dependency:


image::images/property-editors_date-editor-9.png[]

Now you are ready to make use of the date picker. This will involve implementing a couple of NetBeans-specific interfaces:

* ExPropertyEditor—a property editor interface through which the property sheet can pass an "environment" (`PropertyEnv`) object that gives the editor access to the `Property` object it is editing and more.
* InplaceEditor.Factory—an interface for objects that own an `InplaceEditor`.
* InplaceEditor—an interface that allows a custom component to be provided for display in the property sheet.

You will implement `InplaceEditor.Factory` and `ExPropertyEditor` directly on `DatePropertyEditor`, and then create an `InplaceEditor` nested class:


[start=1]
1. Change the signature of `DatePropertyEditor` as follows:

[source,java]
----

public class DatePropertyEditor extends PropertyEditorSupport *implements ExPropertyEditor, InplaceEditor.Factory* {
----


[start=2]
1. As in earlier examples, press Ctrl-Shift-I to Fix Imports and then use the "Implement All Abstract Methods" to cause the missing methods to be added.


[start=3]
1. Add the following methods to `DatePropertyEditor`:

[source,java]
----

@Override
public void attachEnv(PropertyEnv env) {
    env.registerInplaceEditorFactory(this);
}

private InplaceEditor ed = null;

@Override
public InplaceEditor getInplaceEditor() {
    if (ed == null) {
        ed = new Inplace();
    }
    return ed;
}
----


[start=4]
1. Now you need to implement the `InplaceEditor` itself. This will be an object that owns a swingx `JXDatePicker` 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 `Inplace` as a static nested class inside `DatePropertyEditor`:

[source,java]
----

private static class Inplace implements InplaceEditor {

    private final JXDatePicker picker = new JXDatePicker();
    private PropertyEditor editor = null;

    @Override
    public void connect(PropertyEditor propertyEditor, PropertyEnv env) {
        editor = propertyEditor;
        reset();
    }

    @Override
    public JComponent getComponent() {
        return picker;
    }

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

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

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

    @Override
    public boolean supportsTextEntry() {
        return true;
    }

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

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

    @Override
    public PropertyEditor getPropertyEditor() {
        return editor;
    }

    @Override
    public PropertyModel getPropertyModel() {
        return model;
    }

    private PropertyModel model;

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

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

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

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

}
----


[start=5]
1. If you haven't already, press Ctrl-Shift-I to Fix Imports.


[start=6]
1. Run the Event Manager again, select an instance of `EventNode`, 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:


image::images/property-editors_date-editor-result-1.png[]


== Registering DatePropertyEditor Globally

Often it is useful to register a property editor to be used for all properties of a given type. Indeed, your `DatePropertyEditor` is generally useful for any property of the type `java.util.Date`. 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.

Here is how to register `DatePropertyEditor` so that any property of the type `java.util.Date` will use `DatePropertyEditor` in the property sheet:


[start=1]
1. Annotate the  ``DatePropertyEditor``  class as follows: link:http://bits.netbeans.org/dev/javadoc/org-openide-nodes/org/openide/nodes/PropertyEditorRegistration.html[@PropertyEditorRegistration(targetType = Date.class)]

[source,java]
----

public class DatePropertyEditor extends PropertyEditorSupport implements ExPropertyEditor, InplaceEditor.Factory {
----

This code will register your custom `DatePropertyEditor` as the default editor for all properties of the type `java.util.Date` throughout the system.


[start=2]
1. In the  ``EventNode``  class, delete this line, which is not needed anymore, thanks to the previous step:

[source,java]
----

dateProp.setPropertyEditorClass(DatePropertyEditor.class);
----


== Using PropertyPanel

While we won't cover it in detail, it is worth mentioning that the property sheet is not the only place that `Node.Property` objects are useful; there is also a convenient UI class in the `org.openide.explorer.PropertySheet` class called `PropertyPanel`. 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 `somePropertyPanel.setPreferences(PropertyPanel.PREF_CUSTOM_EDITOR)`, it will display the custom editor for a `Property`. 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.

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