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    <h1>NetBeans Platform Quick Start</h1>

    <p>Welcome to the <a href="https://platform.netbeans.org/"><b>NetBeans Platform</b></a>!

    <p>The key benefit of the NetBeans Platform is its modular architecture. Secondary
     benefits are the NetBeans Platform's reliance on the Swing UI toolkit, which is the
     official toolkit for creating user interfaces in Java, in combination with the
     NetBeans IDE's award winning "Matisse" GUI Builder.

    <p>In this quick start, you are introduced to the benefit and usage of modularity via
     a very simple example, contributed by Thomas W&#252;rthinger, who is currently a
     PhD student at the Johannes Kepler University in Linz, Austria. Once you have
     grasped the concepts introduced in this quick start, you will be ready to
     step onto the <a href="https://netbeans.org/kb/trails/platform.html">NetBeans Platform Learning Trail</a>,
     providing a very rich variety of tutorials for many different scenarios
     relating to the NetBeans Platform.

 <p class="tips"> If you are new to the NetBeans Platform, it is highly
  recommended to watch the screencast series <a href="https://platform.netbeans.org/tutorials/nbm-10-top-apis.html">Top 10 NetBeans APIs</a>.

    <p><b>Contents</b></p>
       <img  src="../images/articles/67/netbeans-stamp6567.gif" class="stamp" width="114" height="114" alt="Content on this page applies to NetBeans IDE 6.5" title="Content on this page applies to NetBeans IDE 6.5"> </p>
       <ul class="toc">
         <li><a href="#single">A Single Module NetBeans Platform Application</a></li>
         <li><a href="#lookup">A Modular Application Using Lookup</a>
         <li><a href="#listener">LookupListener and InstanceContent</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</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><b class="notes">Note:</b> Even though it is a separate product, there is no
     need to download the NetBeans Platform separately. Typically, you develop the
     application in NetBeans IDE and then exclude the modules that are specific to
     the IDE but that are superfluous to your application.

     <!-- ===================================================================================== -->

     <h2 class="tutorial"><a name="single"></a>A Single Module NetBeans Platform Application</h2>

     <p>We start by simply creating a new NetBeans Platform application,
      containing a single module.

     <ol>

          <p><li><p>Choose File | New Project and then choose NetBeans Modules.
           Select "NetBeans Platform Application". You should see this:</p>
          <p><p align="left"><img border="1" src="../images/tutorials/quickstart-platform/fig-1.png" alt="Fig 1">
          <p>Click Next.</p>

          <p><li><p>Call your new application "WordApp" and make it the IDE's main project:</p>
          <p><p align="left"><img border="1" src="../images/tutorials/quickstart-platform/fig-2.png" alt="Fig 2">
          <p class="tips"> The IDE's main project is started when the
          global project command "Run Project" is invoked.</p>
          <p>Click Finish.</p>

          <p><li><p>Expand the new application in the Projects window,
          right-click the Modules node, and choose "Add New". Call the new
          module "WordEngine":</p>
           <p><p align="left"><img border="1" src="../images/tutorials/quickstart-platform/fig-3.png"/>
          <p>Click Next.</p>

          <p><li><p>Specify a unique name for the module, which is its code name
           base, as well as a name that will be displayed in the Projects window:</p>
           <p><p align="left"><img border="1" src="../images/tutorials/quickstart-platform/fig-4.png"/>
           <p>Click Finish. The new module is created and its structure is
           shown in the Projects window.

          <p><li><p>Right-click the "WordEngine" module and choose New | Other.
          In the Module Development category, select "Window Component":
          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-17.png"/>

          <p><p>Click Next. You should now see this:</p>
          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-5.png"/>
          <p>Click Next.</p>

          <p><li><p>Set the class name prefix to "Text" and the package to "org.demo.wordengine":</p>
          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-6.png"/>
          <p>Click Finish. The new window is added to the source structure
          of your module, together with some ancillary XML files.</p>

          <p><li><p>Now double click on the file "TextTopComponent.java" to open
          it in the Design view of the "Matisse" GUI Builder. Use the Palette (Ctrl-Shift-8) to
          drag and drop a button and a text area onto the window:</p>

          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-7.png"/>

          <p>Right-click the text area, choose "Change Variable Name", and then
           name it "text". That is the name that will enable you to access the
           component from your code. Set the text of the button to "Filter!"

          <p><li><p>Double click on the button, causing an event handling method
          to automatically be created in the Source editor. The method is called whenever the button is clicked. Change the body
          of the method to the following code.</p>
 <p><pre class="examplecode">private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
    String s = text.getText();
    s = s.toUpperCase();
    text.setText(s);
 }</pre>

          <p><li><p>Right-click the application and choose Run. Doing so will start up your
          new NetBeans Platform application and install your module. Your new application
          should look as follows:</p>
          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-8.png"/>

          <p><li><p>Choose Window | Text, enter a text in the text area, and click "Filter!".
          You should see that the text is now shown in uppercase:</p>
          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-9.png"/>

     </ol>

 <p>You have learned how to create a new NetBeans Platform application and how
  to add new modules to it.

     <!-- ===================================================================================== -->

     <h2 class="tutorial"><a name="lookup"></a>A Modular Application Using Lookup</h2>

     <p>We create two additional modules. The first new module
      defines a service, which the second module provides to
      the module we defined in the previous section.

     <ol>
          <p><li><p>Expand the new application in the Projects window,
          right-click the Modules node, and choose "Add New". Call the new
          module "TextFilter", with code name base "org.demo.textfilter",
          complete the wizard, which adds the module to your previously created
          application, as you did in the previous section.</p>

          <p><li><p>Right-click the "TextFilter" module and choose
          New | Java Interface. Name the Java interface "TextFilter",
          in the package "org.demo.textfilter", and use the editor
          to define it as follows:

 <p><pre class="examplecode">package org.demo.textfilter;

 public interface TextFilter {

     String process(String s);

 }
 </pre>

          <p><li><p>Right-click the "TextFilter" module,
          choose Properties, and use the "API Versioning"
          tab so specify that the package containing the
          interface should be available throughout the
          application:</p>

          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-10.png"/>

          <p><li><p>Create a third module in your application,
          name it "MyFilter", with "org.demo.myfilter" as the
          code name base.</p>

          <p><li><p>Add a dependency in the
          Project Properties dialog of the newly created
          "MyFilter" module
          to the "TextFilter" module:</p>

          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-11.png"/>

          <p><li>Because of the dependency you defined above,
          you can now implement the
          interface defined in the second module:

 <p><pre class="examplecode">package org.demo.myfilter;

 import org.demo.textfilter.TextFilter;

 public class UpperCaseFilter implements TextFilter {

     public String process(String s) {
         return s.toUpperCase();
     }

 }</pre>

         <p><li><p>Next, you need to publish the implementation
          of the interface, using the standard JDK 6 way of
          doing so. In the "MyFilter" module, create a
          folder structure "src/META-INF/services", add to
          it a file named after the fully qualified name
          of the interface, containing one
          line consisting of the fully qualified name
          of the implementation:</p>

          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-13.png"/>

          <p class="tips"> An empty file can be created
           via Other | Empty File in the New File dialog:</p>

          <p><img border="1" src="../images/tutorials/quickstart-platform/fig-12.png"/>

          <p><li><p>The code that handles a click on the
         filter button now needs to be changed, so that an
         implementor of the interface "TextFilter" is located
         and loaded.
         When such an implementor is found, it is invoked to
         filter the text.</p>
         <p>Before we can do this, we need to
         add a dependency in the Project Properties dialog of
         the "WordEngine" module to the "TextFilter" module:</p>

         <p><img src="../images/tutorials/quickstart-platform/fig-14.png"/>

 <p>Now, you can load implementations of the
 "TextFilter" class, as shown below:</p>

 <p><pre class="examplecode">private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
     String s = text.getText();
     <b>TextFilter filter = Lookup.getDefault().lookup(TextFilter.class)</b>;
     if (filter != null) {
 	 s = filter.process(s);
     }
     text.setText(s);
 }</pre>

          <p class="tips"> The above could be done via the
           JDK 6 "ServiceLoader" class, except that the
           "Lookup" class can be used in JDK's prior
           to JDK 6. Aside from that, the "Lookup" class
           has a number of additional features, as the
           next section will illustrate.</p>

     </ol>

      <p>Now you are ready to run the code and check
          that everything works just as before. While the functionality
          is the same, the new modular design offers a clear separation
          between the graphical user interface and the implementation
          of the filter. The new application can also be extended
          quite easily, simply by adding new service providers to
          the application's classpath.</p>

 <p>As an exercise, you could change the code,
          so that ALL found text filters (use the method "lookupAll")
          are applied consecutively on the text. For example,
          add a text filter
          implementation that removes all whitespaces and then test
          the resulting application.</p>

     <!-- ===================================================================================== -->

     <h2 class="tutorial"><a name="listener"></a>LookupListener and InstanceContent</h2>

     <p>We create a fourth module, which receives texts
      dynamically whenever we click the "Filter!" button
      in our first module.

     <ol>
          <p><li><p>In the first module, change the
          constructor of the "TextTopComponent" as follows:</p>

 <p><pre class="examplecode"><b>private InstanceContent content;</b>

 private TextTopComponent() {
     initComponents();
     setName(NbBundle.getMessage(TextTopComponent.class, "CTL_TextTopComponent"));
     setToolTipText(NbBundle.getMessage(TextTopComponent.class, "HINT_TextTopComponent"));
 //        setIcon(Utilities.loadImage(ICON_PATH, true));

     <b>content = new InstanceContent();
     associateLookup(new AbstractLookup(content));</b>

 }</pre>

          <p><li><p>Change the code of the filter
          button so that the old value is added to
          the <tt>InstanceContent</tt> object when the button is clicked.</p>

 <p><pre class="examplecode">private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
     String s = text.getText();
     TextFilter filter = Lookup.getDefault().lookup(TextFilter.class);
     if (filter != null) {
         <b>content.add(s);</b>
         s = filter.process(s);
     }
     text.setText(s);
 }</pre>

          <p><li><p>Create a new module called "History"
          with code name base "com.demo.history".
          <p><li>In the History module, create a
          new window component with prefix "History",
          in the "com.demo.history" package. Specify that
          it should appear in the "editor" position. Once
          you have created the window, add a
          text area to it. Change the variable
          name of the text area to "historyText".</p>

          <p><li><p>Add code to the constructor of the HistoryTopComponent class so
          that it listens to the lookup of the <tt>String</tt> class
          of the current active window. It displays all retrieved
          <tt>String</tt> objects in the text area:</p>

 <p><pre class="examplecode"><b>private Lookup.Result result;</b>

 private HistoryTopComponent() {

     ...

     <b>result = org.openide.util.Utilities.actionsGlobalContext().lookupResult(String.class);
     result.addLookupListener(new LookupListener() {
         public void resultChanged(LookupEvent e) {
             historyText.setText(result.allInstances().toString());
         }
     });</b>
 }</pre>

      <p><li>Then you can start the application and
      experiment with it. The result should look similar
      to the one shown in the screenshot below:</p>

 <p><img border="1" src="../images/tutorials/quickstart-platform/fig-15.png"/>

 <p>As an exercise, you can change the type of the
  lookup result from <tt>String</tt> to <tt>Object</tt> and see
  what happens when you select different windows.</p>

  </ol>

 <p>Congratulations! At this stage, with very little coding,
  you have created a small example of a modular
  application:

  <p><img border="1" src="../images/tutorials/quickstart-platform/fig-16.png"/>

 <p>The application consists of 4 modules. Code from one module can only
  be used by another module if (1) the first module explicitly exposes
  packages and (2) the second module sets a dependency on the first module.
  In this way, the NetBeans Platform helps to organize your code in a
  strict modular architecture, ensuring that code isn't reused randomly
  but only when there are contracts set between the modules that provide
 the code.</p><p>Secondly, the <tt>Lookup</tt> class has been introduced as
  a mechanism for communicating between modules, as an extension of the
  JDK 6 ServiceLoader approach. Implementations are loaded via their
  interfaces. Without using any code from an implementation, the "WordEngine"
  module is able to display the service provided by the implementor. Loose
 coupling is provided to NetBeans Platform applications in this way.</p>

 <p class="tips"> To continue learning about modularity
  and the NetBeans Platform, head on to
  the 4-part "NetBeans Platform Selection
  Management" series, <a href="https://platform.netbeans.org/tutorials/nbm-selection-1.html">which starts here</a>.
  After that, get started with the <a href="https://netbeans.org/kb/trails/platform.html">NetBeans Platform Learning Trail</a>, choosing
  the tutorials that are most relevant to your particular business scenario. Also,
  whenever you have questions about the NetBeans Platform, of any kind, feel free
  to write to the mailing list, dev@platform.netbeans.org, its related
 archive <a href="https://netbeans.org/projects/platform/lists/dev/archive">is here</a>.</p>

  <p>Have fun with the NetBeans Platform and see you on the mailing list!</p>


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	content="A short guide to getting started with the NetBeans Platform.">
	</head>
	<body>

	<h1>NetBeans Platform Quick Start</h1>

	<p>Welcome to the <a href="https://platform.netbeans.org/"><b>NetBeans Platform</b></a>!

	<p>The key benefit of the NetBeans Platform is its modular architecture. Secondary
	benefits are the NetBeans Platform's reliance on the Swing UI toolkit, which is the
	official toolkit for creating user interfaces in Java, in combination with the
	NetBeans IDE's award winning "Matisse" GUI Builder.

	<p>In this quick start, you are introduced to the benefit and usage of modularity via
	a very simple example, contributed by Thomas Würthinger, who is currently a
	PhD student at the Johannes Kepler University in Linz, Austria. Once you have
	grasped the concepts introduced in this quick start, you will be ready to
	step onto the <a href="https://netbeans.org/kb/trails/platform.html">NetBeans Platform Learning Trail</a>,
	providing a very rich variety of tutorials for many different scenarios
	relating to the NetBeans Platform.

	<p class="tips"> If you are new to the NetBeans Platform, it is highly
	recommended to watch the screencast series <a href="https://platform.netbeans.org/tutorials/nbm-10-top-apis.html">Top 10 NetBeans APIs</a>.

	<p><b>Contents</b></p>
	<img src="../images/articles/67/netbeans-stamp6567.gif" class="stamp" width="114" height="114" alt="Content on this page applies to NetBeans IDE 6.5" title="Content on this page applies to NetBeans IDE 6.5"> </p>
	<ul class="toc">
	<li><a href="#single">A Single Module NetBeans Platform Application</a></li>
	<li><a href="#lookup">A Modular Application Using Lookup</a>
	<li><a href="#listener">LookupListener and InstanceContent</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</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><b class="notes">Note:</b> Even though it is a separate product, there is no
	need to download the NetBeans Platform separately. Typically, you develop the
	application in NetBeans IDE and then exclude the modules that are specific to
	the IDE but that are superfluous to your application.

	<!-- ===================================================================================== -->

	<h2 class="tutorial"><a name="single"></a>A Single Module NetBeans Platform Application</h2>

	<p>We start by simply creating a new NetBeans Platform application,
	containing a single module.

	<ol>

	<p><li><p>Choose File \| New Project and then choose NetBeans Modules.
	Select "NetBeans Platform Application". You should see this:</p>
	<p><p align="left"><img border="1" src="../images/tutorials/quickstart-platform/fig-1.png" alt="Fig 1">
	<p>Click Next.</p>

	<p><li><p>Call your new application "WordApp" and make it the IDE's main project:</p>
	<p><p align="left"><img border="1" src="../images/tutorials/quickstart-platform/fig-2.png" alt="Fig 2">
	<p class="tips"> The IDE's main project is started when the
	global project command "Run Project" is invoked.</p>
	<p>Click Finish.</p>

	<p><li><p>Expand the new application in the Projects window,
	right-click the Modules node, and choose "Add New". Call the new
	module "WordEngine":</p>
	<p><p align="left"><img border="1" src="../images/tutorials/quickstart-platform/fig-3.png"/>
	<p>Click Next.</p>

	<p><li><p>Specify a unique name for the module, which is its code name
	base, as well as a name that will be displayed in the Projects window:</p>
	<p><p align="left"><img border="1" src="../images/tutorials/quickstart-platform/fig-4.png"/>
	<p>Click Finish. The new module is created and its structure is
	shown in the Projects window.

	<p><li><p>Right-click the "WordEngine" module and choose New \| Other.
	In the Module Development category, select "Window Component":
	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-17.png"/>

	<p><p>Click Next. You should now see this:</p>
	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-5.png"/>
	<p>Click Next.</p>

	<p><li><p>Set the class name prefix to "Text" and the package to "org.demo.wordengine":</p>
	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-6.png"/>
	<p>Click Finish. The new window is added to the source structure
	of your module, together with some ancillary XML files.</p>

	<p><li><p>Now double click on the file "TextTopComponent.java" to open
	it in the Design view of the "Matisse" GUI Builder. Use the Palette (Ctrl-Shift-8) to
	drag and drop a button and a text area onto the window:</p>

	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-7.png"/>

	<p>Right-click the text area, choose "Change Variable Name", and then
	name it "text". That is the name that will enable you to access the
	component from your code. Set the text of the button to "Filter!"

	<p><li><p>Double click on the button, causing an event handling method
	to automatically be created in the Source editor. The method is called whenever the button is clicked. Change the body
	of the method to the following code.</p>
	<p><pre class="examplecode">private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
	String s = text.getText();
	s = s.toUpperCase();
	text.setText(s);
	}</pre>

	<p><li><p>Right-click the application and choose Run. Doing so will start up your
	new NetBeans Platform application and install your module. Your new application
	should look as follows:</p>
	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-8.png"/>

	<p><li><p>Choose Window \| Text, enter a text in the text area, and click "Filter!".
	You should see that the text is now shown in uppercase:</p>
	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-9.png"/>

	</ol>

	<p>You have learned how to create a new NetBeans Platform application and how
	to add new modules to it.

	<!-- ===================================================================================== -->

	<h2 class="tutorial"><a name="lookup"></a>A Modular Application Using Lookup</h2>

	<p>We create two additional modules. The first new module
	defines a service, which the second module provides to
	the module we defined in the previous section.

	<ol>
	<p><li><p>Expand the new application in the Projects window,
	right-click the Modules node, and choose "Add New". Call the new
	module "TextFilter", with code name base "org.demo.textfilter",
	complete the wizard, which adds the module to your previously created
	application, as you did in the previous section.</p>

	<p><li><p>Right-click the "TextFilter" module and choose
	New \| Java Interface. Name the Java interface "TextFilter",
	in the package "org.demo.textfilter", and use the editor
	to define it as follows:

	<p><pre class="examplecode">package org.demo.textfilter;

	public interface TextFilter {

	String process(String s);

	}
	</pre>

	<p><li><p>Right-click the "TextFilter" module,
	choose Properties, and use the "API Versioning"
	tab so specify that the package containing the
	interface should be available throughout the
	application:</p>

	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-10.png"/>

	<p><li><p>Create a third module in your application,
	name it "MyFilter", with "org.demo.myfilter" as the
	code name base.</p>

	<p><li><p>Add a dependency in the
	Project Properties dialog of the newly created
	"MyFilter" module
	to the "TextFilter" module:</p>

	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-11.png"/>

	<p><li>Because of the dependency you defined above,
	you can now implement the
	interface defined in the second module:

	<p><pre class="examplecode">package org.demo.myfilter;

	import org.demo.textfilter.TextFilter;

	public class UpperCaseFilter implements TextFilter {

	public String process(String s) {
	return s.toUpperCase();
	}

	}</pre>

	<p><li><p>Next, you need to publish the implementation
	of the interface, using the standard JDK 6 way of
	doing so. In the "MyFilter" module, create a
	folder structure "src/META-INF/services", add to
	it a file named after the fully qualified name
	of the interface, containing one
	line consisting of the fully qualified name
	of the implementation:</p>

	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-13.png"/>

	<p class="tips"> An empty file can be created
	via Other \| Empty File in the New File dialog:</p>

	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-12.png"/>

	<p><li><p>The code that handles a click on the
	filter button now needs to be changed, so that an
	implementor of the interface "TextFilter" is located
	and loaded.
	When such an implementor is found, it is invoked to
	filter the text.</p>
	<p>Before we can do this, we need to
	add a dependency in the Project Properties dialog of
	the "WordEngine" module to the "TextFilter" module:</p>

	<p><img src="../images/tutorials/quickstart-platform/fig-14.png"/>

	<p>Now, you can load implementations of the
	"TextFilter" class, as shown below:</p>

	<p><pre class="examplecode">private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
	String s = text.getText();
	<b>TextFilter filter = Lookup.getDefault().lookup(TextFilter.class)</b>;
	if (filter != null) {
	s = filter.process(s);
	}
	text.setText(s);
	}</pre>

	<p class="tips"> The above could be done via the
	JDK 6 "ServiceLoader" class, except that the
	"Lookup" class can be used in JDK's prior
	to JDK 6. Aside from that, the "Lookup" class
	has a number of additional features, as the
	next section will illustrate.</p>

	</ol>

	<p>Now you are ready to run the code and check
	that everything works just as before. While the functionality
	is the same, the new modular design offers a clear separation
	between the graphical user interface and the implementation
	of the filter. The new application can also be extended
	quite easily, simply by adding new service providers to
	the application's classpath.</p>

	<p>As an exercise, you could change the code,
	so that ALL found text filters (use the method "lookupAll")
	are applied consecutively on the text. For example,
	add a text filter
	implementation that removes all whitespaces and then test
	the resulting application.</p>

	<!-- ===================================================================================== -->

	<h2 class="tutorial"><a name="listener"></a>LookupListener and InstanceContent</h2>

	<p>We create a fourth module, which receives texts
	dynamically whenever we click the "Filter!" button
	in our first module.

	<ol>
	<p><li><p>In the first module, change the
	constructor of the "TextTopComponent" as follows:</p>

	<p><pre class="examplecode"><b>private InstanceContent content;</b>

	private TextTopComponent() {
	initComponents();
	setName(NbBundle.getMessage(TextTopComponent.class, "CTL_TextTopComponent"));
	setToolTipText(NbBundle.getMessage(TextTopComponent.class, "HINT_TextTopComponent"));
	// setIcon(Utilities.loadImage(ICON_PATH, true));

	<b>content = new InstanceContent();
	associateLookup(new AbstractLookup(content));</b>

	}</pre>

	<p><li><p>Change the code of the filter
	button so that the old value is added to
	the <tt>InstanceContent</tt> object when the button is clicked.</p>

	<p><pre class="examplecode">private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
	String s = text.getText();
	TextFilter filter = Lookup.getDefault().lookup(TextFilter.class);
	if (filter != null) {
	<b>content.add(s);</b>
	s = filter.process(s);
	}
	text.setText(s);
	}</pre>

	<p><li><p>Create a new module called "History"
	with code name base "com.demo.history".
	<p><li>In the History module, create a
	new window component with prefix "History",
	in the "com.demo.history" package. Specify that
	it should appear in the "editor" position. Once
	you have created the window, add a
	text area to it. Change the variable
	name of the text area to "historyText".</p>

	<p><li><p>Add code to the constructor of the HistoryTopComponent class so
	that it listens to the lookup of the <tt>String</tt> class
	of the current active window. It displays all retrieved
	<tt>String</tt> objects in the text area:</p>

	<p><pre class="examplecode"><b>private Lookup.Result result;</b>

	private HistoryTopComponent() {

	...

	<b>result = org.openide.util.Utilities.actionsGlobalContext().lookupResult(String.class);
	result.addLookupListener(new LookupListener() {
	public void resultChanged(LookupEvent e) {
	historyText.setText(result.allInstances().toString());
	}
	});</b>
	}</pre>

	<p><li>Then you can start the application and
	experiment with it. The result should look similar
	to the one shown in the screenshot below:</p>

	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-15.png"/>

	<p>As an exercise, you can change the type of the
	lookup result from <tt>String</tt> to <tt>Object</tt> and see
	what happens when you select different windows.</p>

	</ol>

	<p>Congratulations! At this stage, with very little coding,
	you have created a small example of a modular
	application:

	<p><img border="1" src="../images/tutorials/quickstart-platform/fig-16.png"/>

	<p>The application consists of 4 modules. Code from one module can only
	be used by another module if (1) the first module explicitly exposes
	packages and (2) the second module sets a dependency on the first module.
	In this way, the NetBeans Platform helps to organize your code in a
	strict modular architecture, ensuring that code isn't reused randomly
	but only when there are contracts set between the modules that provide
	the code.</p><p>Secondly, the <tt>Lookup</tt> class has been introduced as
	a mechanism for communicating between modules, as an extension of the
	JDK 6 ServiceLoader approach. Implementations are loaded via their
	interfaces. Without using any code from an implementation, the "WordEngine"
	module is able to display the service provided by the implementor. Loose
	coupling is provided to NetBeans Platform applications in this way.</p>

	<p class="tips"> To continue learning about modularity
	and the NetBeans Platform, head on to
	the 4-part "NetBeans Platform Selection
	Management" series, <a href="https://platform.netbeans.org/tutorials/nbm-selection-1.html">which starts here</a>.
	After that, get started with the <a href="https://netbeans.org/kb/trails/platform.html">NetBeans Platform Learning Trail</a>, choosing
	the tutorials that are most relevant to your particular business scenario. Also,
	whenever you have questions about the NetBeans Platform, of any kind, feel free
	to write to the mailing list, dev@platform.netbeans.org, its related
	archive <a href="https://netbeans.org/projects/platform/lists/dev/archive">is here</a>.</p>

	<p>Have fun with the NetBeans Platform and see you on the mailing list!</p>



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