bundles/org.eclipse.jdt.doc.isv/guide/jdt_int_model.htm - platform/eclipse.platform.common - Git at Google

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 <body>
 <h2>Java model</h2>
 <p>The Java model is the set of classes that model the objects associated with creating, editing,
 and building a Java program. The Java model classes are defined in <b><a href=
 "../reference/api/org/eclipse/jdt/core/package-summary.html">org.eclipse.jdt.core</a></b>.&nbsp;

 These classes implement Java specific behavior for resources and further decompose Java resources
 into model elements.</p>
 <h3>Java elements</h3>
 <p>The package <a href=
 "../reference/api/org/eclipse/jdt/core/package-summary.html"><b>org.eclipse.jdt.core</b></a>
 defines the classes that model the elements that compose a Java program. The JDT uses an in-memory
 object model to represent the structure of a Java program. This structure is derived from the
 project's class path. The model is hierarchical. Elements of a program can be decomposed into child
 elements.</p>
 <p>Manipulating Java elements is similar to manipulating resource objects.&nbsp; When you work with
 a Java element, you are actually working with a <b>handle</b> to some underlying model
 object.&nbsp; You must use the <b>exists()</b> protocol to determine whether the element is
 actually present in the workspace.&nbsp;</p>

 <p>The following table summarizes the different kinds of Java elements.</p>
 <table border="1">
 <tbody>
 <tr>
 <th rowspan="1" colspan="1">Element</th>
 <th rowspan="1" colspan="1">Description</th>
 </tr>
 <tr>
 <td><a href="../reference/api/org/eclipse/jdt/core/IJavaModel.html"><b>IJavaModel</b></a></td>
 <td>Represents the root Java element, corresponding to the workspace. The parent of all projects
 with the Java nature. It also gives you access to the projects without the java nature.</td>
 </tr>
 <tr>

 <td><a href="../reference/api/org/eclipse/jdt/core/IJavaProject.html"><b>IJavaProject</b></a></td>
 <td>Represents a Java project in the workspace. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IJavaModel.html"><b>IJavaModel</b></a>)</td>
 </tr>

 <tr>
 <td><a href="../reference/api/org/eclipse/jdt/core/IModuleDescription.html"><b>IModuleDescription</b></a></td>
 <td>Represents a Java module descriptor. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IJavaProject.html"><b>IJavaProject</b></a>)</td>
 </tr>

 <tr>
 <td><a href=
 "../reference/api/org/eclipse/jdt/core/IPackageFragmentRoot.html"><b>IPackageFragmentRoot</b></a></td>
 <td>Represents a set of package fragments, and maps the fragments to an underlying resource which
 is either a folder, JAR, or ZIP file. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IJavaProject.html"><b>IJavaProject</b></a>)</td>
 </tr>
 <tr>
 <td><a href=
 "../reference/api/org/eclipse/jdt/core/IPackageFragment.html"><b>IPackageFragment</b></a></td>

 <td>Represents the portion of the workspace that corresponds to an entire package, or a portion of
 the package. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IPackageFragmentRoot.html"><b>IPackageFragmentRoot</b></a>
 )</td>
 </tr>
 <tr>
 <td><a href=
 "../reference/api/org/eclipse/jdt/core/ICompilationUnit.html"><b>ICompilationUnit</b></a></td>
 <td>Represents a Java source (<b>.java</b>) file. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IPackageFragment.html"><b>IPackageFragment</b></a> )</td>
 </tr>

 <tr>
 <td><a href=
 "../reference/api/org/eclipse/jdt/core/IPackageDeclaration.html"><b>IPackageDeclaration</b></a></td>
 <td>Represents a package declaration in a compilation unit. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/ICompilationUnit.html"><b>ICompilationUnit</b></a> )</td>
 </tr>
 <tr>
 <td><a href=
 "../reference/api/org/eclipse/jdt/core/IImportContainer.html"><b>IImportContainer</b></a></td>
 <td>Represents the collection of package import declarations in a compilation unit. (Child of
 <a href="../reference/api/org/eclipse/jdt/core/ICompilationUnit.html"><b>ICompilationUnit</b></a>
 )</td>

 </tr>
 <tr>
 <td><a href=
 "../reference/api/org/eclipse/jdt/core/IImportDeclaration.html"><b>IImportDeclaration</b></a></td>
 <td>Represents a single package import declaration. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IImportContainer.html"><b>IImportContainer</b></a> )</td>
 </tr>
 <tr>
 <td><a href="../reference/api/org/eclipse/jdt/core/IType.html"><b>IType</b></a></td>
 <td>Represents either a source type inside a compilation unit, or a binary type inside a class
 file.</td>
 </tr>
 <tr>

 <td><a href="../reference/api/org/eclipse/jdt/core/IField.html"><b>IField</b></a></td>
 <td>Represents a field inside a type. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IType.html"><b>IType</b></a> )</td>
 </tr>
 <tr>
 <td><a href="../reference/api/org/eclipse/jdt/core/IMethod.html"><b>IMethod</b></a></td>
 <td>Represents a method or constructor inside a type. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IType.html"><b>IType</b></a> )</td>
 </tr>

 <tr>
 <td><a href="../reference/api/org/eclipse/jdt/core/IInitializer.html"><b>IInitializer</b></a></td>
 <td>Represents a static or instance initializer inside a type. (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IType.html"><b>IType</b></a> )</td>
 </tr>
 <tr>
 <td><a href="../reference/api/org/eclipse/jdt/core/IClassFile.html"><b>IClassFile</b></a></td>
 <td>Represents a compiled (binary) type.&nbsp; (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IPackageFragment.html"><b>IPackageFragment</b></a> )</td>

 </tr>

 <tr>
 <td><a href="../reference/api/org/eclipse/jdt/core/IModularClassFile.html"><b>IModularClassFile</b></a></td>
 <td>Represents the class file of a module description ("module-info.class").&nbsp; (Child of <a href=
 "../reference/api/org/eclipse/jdt/core/IPackageFragment.html"><b>IPackageFragment</b></a> )</td>
 </tr>

 <tr>
 <td><a href=
 "../reference/api/org/eclipse/jdt/core/ITypeParameter.html"><b>ITypeParameter</b></a></td>
 <td>Represents a type parameter.&nbsp; (Not a child of any Java element, it is obtained using
 <a href=
 "../reference/api/org/eclipse/jdt/core/IType.html#getTypeParameter(java.lang.String)"><b>IType.getTypeParameter(String)</b></a>
 or <a href=
 "../reference/api/org/eclipse/jdt/core/IMethod.html#getTypeParameter(java.lang.String)"><b>IMethod.getTypeParameter(String)</b></a>)</td>
 </tr>
 <tr>
 <td><a href=
 "../reference/api/org/eclipse/jdt/core/ILocalVariable.html"><b>ILocalVariable</b></a></td>

 <td>Represents a local variable in a method or an initializer.&nbsp; (Not a child of any Java
 element, it is obtained using <a href=
 "../reference/api/org/eclipse/jdt/core/ICodeAssist.html#codeSelect(int,%20int)"><b>ICodeAssist.codeSelect(int,
 int)</b></a>)</td>
 </tr>
 <tr>
 <td><a href="../reference/api/org/eclipse/jdt/core/IAnnotation.html"><b>IAnnotation</b></a></td>
 <td>Represents a Java 5 annotation. (Not a child of any Java element, it is obtained using <a href=
 "../reference/api/org/eclipse/jdt/core/IAnnotatable.html#getAnnotation(java.lang.String)"><b>IAnnotatable.getAnnotation(String)</b></a>
 or <a href=
 "../reference/api/org/eclipse/jdt/core/IAnnotatable.html#getAnnotations()"><b>IAnnotatable.getAnnotations()</b></a>)</td>

 </tr>
 <tr>
 <td><a href="../reference/api/org/eclipse/jdt/core/IAnnotatable.html"><b>IAnnotatable</b></a></td>
 <td>Represents a type, a field, a method, a local variable, or a package declaration that can be
 annotated with one or several <a href=
 "../reference/api/org/eclipse/jdt/core/IAnnotation.html"><b>IAnnotation</b></a>s.</td>
 </tr>
 </tbody>
 </table>
 <p>All Java elements support the <a href=
 "../reference/api/org/eclipse/jdt/core/IJavaElement.html"><b>IJavaElement</b></a> interface.</p>
 <p>Some of the elements are shown in the Packages view.&nbsp; These elements implement the

 <b><a href="../reference/api/org/eclipse/jdt/core/IOpenable.html">IOpenable</a></b> interface,
 since they must be opened before they can be navigated. The figure below shows how these elements
 are represented in the Packages view.</p>
 <p><img src="images/openables.png" border="0" alt=
 "Packages View showing elements implementing the IOpenable interface" /></p>
 <p>The Java elements that implement <b><a href=
 "../reference/api/org/eclipse/jdt/core/IOpenable.html">IOpenable</a></b> are created primarily from
 information found in the underlying resource files.&nbsp; The same elements are represented
 generically in the resource navigator view.</p>
 <p><img src="images/javanavigator.png" border="0" alt=
 "Resource Navigator showing elements implementing the IOpenable interface" /></p>
 <p>Since 3.3, <b><a href="../reference/api/org/eclipse/jdt/core/IOpenable.html">IOpenable</a></b>s
 that are the root of <b><a href="../reference/api/org/eclipse/jdt/core/IType.html">IType</a></b>s
 implement <b><a href="../reference/api/org/eclipse/jdt/core/ITypeRoot.html">ITypeRoot</a></b> .
 These are <b><a href=
 "../reference/api/org/eclipse/jdt/core/ICompilationUnit.html">ICompilationUnit</a></b> and

 <b><a href="../reference/api/org/eclipse/jdt/core/IClassFile.html">IClassFile</a></b>.</p>
 <p>Other elements correspond to the items that make up a Java compilation unit. The figure below
 shows a Java compilation unit and a content outliner that displays the source elements in the
 compilation unit.</p>
 <img src="images/sourceelements.png" border="0" alt=
 "An editor and a content outliner illustrating the relation between corresponding source elements" />
 <p>These elements implement the <a href=
 "../reference/api/org/eclipse/jdt/core/ISourceReference.html"><b>ISourceReference</b></a>
 interface, since they can provide corresponding source code. (As these elements are selected in the
 content outliner, their corresponding source code is shown in the Java editor).</p>
 <h3>Java elements and their resources</h3>
 <p>Many of the Java elements correspond to generic resources in the workspace.&nbsp; When you want
 to create Java elements from a generic resource the class <a href=
 "../reference/api/org/eclipse/jdt/core/JavaCore.html"><b>JavaCore</b></a> is the best starting
 point. The following code snippet shows how to get Java elements from their corresponding
 resources.</p>

 <pre class="color1">

     private void createJavaElementsFrom(IProject myProject, IFolder myFolder, IFile myFile) {
         IJavaProject myJavaProject= JavaCore.create(myProject);
         if (myJavaProject == null)
             // the project is not configured for Java (has no Java nature)
             return;

         // get a package fragment or package fragment root
         IJavaElement myPackageFragment= JavaCore.create(myFolder);

         // get a .java (compilation unit), .class (class file), or
         // .jar (package fragment root)
         IJavaElement myJavaFile = JavaCore.create(myFile);
     }
 </pre>
 <p>Once you have a Java element, you can use the JDT API to traverse and query the model.&nbsp; You
 may also query the non-Java resources contained in a Java element.&nbsp;</p>
 <pre class="color1">
     private void createJavaElementsFrom(IProject myProject, IFolder myFolder, IFile myFile) throws JavaModelException {
         ...
         // get the non Java resources contained in my project.
         Object[] nonJavaChildren = myJavaProject.getNonJavaResources();
         ...
     }
 </pre>
 <h3>Java projects</h3>
 <p>When you create a Java project from a simple project, <a href=
 "../reference/api/org/eclipse/jdt/core/JavaCore.html"><b>JavaCore</b></a> will check to see if the
 project is configured with the Java nature.&nbsp; The JDT plug-in uses a project nature to
 designate a project as having Java behavior.&nbsp; This nature
 (<b>org.eclipse.jdt.core.JavaCore#NATURE_ID</b> ) is assigned to a project when the "New Java
 project" wizard creates a project.&nbsp; If the Java nature is not configured on a project,

 <a href="../reference/api/org/eclipse/jdt/core/JavaCore.html"><b>JavaCore</b></a> will return null
 when asked to create the project.</p>
 <p><a href="../reference/api/org/eclipse/jdt/core/JavaCore.html"><b>JavaCore</b></a> is also used
 to maintain the Java class path, including locations for finding source code and libraries, and
 locations for generating output binary (<b>.class</b>) files.</p>
 <p>What are the unique characteristics of Java projects? They record their classpath in a
 "<b>.classpath</b>" file and add the Java incremental project builder to the project's build
 spec.&nbsp; Otherwise, they are just regular projects and can be configured with other natures (and
 other incremental builders) by plug-ins. Plug-ins that want to configure projects with Java
 behavior in addition to their own behavior typically use the <b><a href=
 "../reference/api/org/eclipse/jdt/ui/wizards/NewJavaProjectWizardPage.html">NewJavaProjectWizardPage</a></b>

 to assign the Java nature to the project in addition to their own custom natures or behavior.</p>
 <p><a href="../reference/api/org/eclipse/jdt/core/IJavaModel.html"><b>IJavaModel</b></a> can be
 considered the parent of all projects in the workspace that have the Java project nature (and
 therefore can be treated as an <a href=
 "../reference/api/org/eclipse/jdt/core/IJavaProject.html"><b>IJavaProject</b></a>).</p>
 </body>
 </html>
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	<html lang="en" xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
	<head>
	<meta name="copyright" content=
	"Copyright (c) IBM Corporation and others 2000, 2011. This page is made available under license. For full details see the LEGAL in the documentation book that contains this page." />
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
	<meta http-equiv="Content-Style-Type" content="text/css" />
	<link rel="STYLESHEET" href="../book.css" charset="ISO-8859-1" type="text/css" />
	<title>Java model</title>
	<link rel="stylesheet" type="text/css" href="../book.css" />
	</head>
	<body>
	<h2>Java model</h2>
	<p>The Java model is the set of classes that model the objects associated with creating, editing,
	and building a Java program. The Java model classes are defined in <b><a href=
	"../reference/api/org/eclipse/jdt/core/package-summary.html">org.eclipse.jdt.core</a></b>.

	These classes implement Java specific behavior for resources and further decompose Java resources
	into model elements.</p>
	<h3>Java elements</h3>
	<p>The package <a href=
	"../reference/api/org/eclipse/jdt/core/package-summary.html"><b>org.eclipse.jdt.core</b></a>
	defines the classes that model the elements that compose a Java program. The JDT uses an in-memory
	object model to represent the structure of a Java program. This structure is derived from the
	project's class path. The model is hierarchical. Elements of a program can be decomposed into child
	elements.</p>
	<p>Manipulating Java elements is similar to manipulating resource objects.  When you work with
	a Java element, you are actually working with a <b>handle</b> to some underlying model
	object.  You must use the <b>exists()</b> protocol to determine whether the element is
	actually present in the workspace. </p>

	<p>The following table summarizes the different kinds of Java elements.</p>
	<table border="1">
	<tbody>
	<tr>
	<th rowspan="1" colspan="1">Element</th>
	<th rowspan="1" colspan="1">Description</th>
	</tr>
	<tr>
	<td><a href="../reference/api/org/eclipse/jdt/core/IJavaModel.html"><b>IJavaModel</b></a></td>
	<td>Represents the root Java element, corresponding to the workspace. The parent of all projects
	with the Java nature. It also gives you access to the projects without the java nature.</td>
	</tr>
	<tr>

	<td><a href="../reference/api/org/eclipse/jdt/core/IJavaProject.html"><b>IJavaProject</b></a></td>
	<td>Represents a Java project in the workspace. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IJavaModel.html"><b>IJavaModel</b></a>)</td>
	</tr>

	<tr>
	<td><a href="../reference/api/org/eclipse/jdt/core/IModuleDescription.html"><b>IModuleDescription</b></a></td>
	<td>Represents a Java module descriptor. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IJavaProject.html"><b>IJavaProject</b></a>)</td>
	</tr>

	<tr>
	<td><a href=
	"../reference/api/org/eclipse/jdt/core/IPackageFragmentRoot.html"><b>IPackageFragmentRoot</b></a></td>
	<td>Represents a set of package fragments, and maps the fragments to an underlying resource which
	is either a folder, JAR, or ZIP file. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IJavaProject.html"><b>IJavaProject</b></a>)</td>
	</tr>
	<tr>
	<td><a href=
	"../reference/api/org/eclipse/jdt/core/IPackageFragment.html"><b>IPackageFragment</b></a></td>

	<td>Represents the portion of the workspace that corresponds to an entire package, or a portion of
	the package. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IPackageFragmentRoot.html"><b>IPackageFragmentRoot</b></a>
	)</td>
	</tr>
	<tr>
	<td><a href=
	"../reference/api/org/eclipse/jdt/core/ICompilationUnit.html"><b>ICompilationUnit</b></a></td>
	<td>Represents a Java source (<b>.java</b>) file. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IPackageFragment.html"><b>IPackageFragment</b></a> )</td>
	</tr>

	<tr>
	<td><a href=
	"../reference/api/org/eclipse/jdt/core/IPackageDeclaration.html"><b>IPackageDeclaration</b></a></td>
	<td>Represents a package declaration in a compilation unit. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/ICompilationUnit.html"><b>ICompilationUnit</b></a> )</td>
	</tr>
	<tr>
	<td><a href=
	"../reference/api/org/eclipse/jdt/core/IImportContainer.html"><b>IImportContainer</b></a></td>
	<td>Represents the collection of package import declarations in a compilation unit. (Child of
	<a href="../reference/api/org/eclipse/jdt/core/ICompilationUnit.html"><b>ICompilationUnit</b></a>
	)</td>

	</tr>
	<tr>
	<td><a href=
	"../reference/api/org/eclipse/jdt/core/IImportDeclaration.html"><b>IImportDeclaration</b></a></td>
	<td>Represents a single package import declaration. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IImportContainer.html"><b>IImportContainer</b></a> )</td>
	</tr>
	<tr>
	<td><a href="../reference/api/org/eclipse/jdt/core/IType.html"><b>IType</b></a></td>
	<td>Represents either a source type inside a compilation unit, or a binary type inside a class
	file.</td>
	</tr>
	<tr>

	<td><a href="../reference/api/org/eclipse/jdt/core/IField.html"><b>IField</b></a></td>
	<td>Represents a field inside a type. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IType.html"><b>IType</b></a> )</td>
	</tr>
	<tr>
	<td><a href="../reference/api/org/eclipse/jdt/core/IMethod.html"><b>IMethod</b></a></td>
	<td>Represents a method or constructor inside a type. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IType.html"><b>IType</b></a> )</td>
	</tr>

	<tr>
	<td><a href="../reference/api/org/eclipse/jdt/core/IInitializer.html"><b>IInitializer</b></a></td>
	<td>Represents a static or instance initializer inside a type. (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IType.html"><b>IType</b></a> )</td>
	</tr>
	<tr>
	<td><a href="../reference/api/org/eclipse/jdt/core/IClassFile.html"><b>IClassFile</b></a></td>
	<td>Represents a compiled (binary) type.  (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IPackageFragment.html"><b>IPackageFragment</b></a> )</td>

	</tr>

	<tr>
	<td><a href="../reference/api/org/eclipse/jdt/core/IModularClassFile.html"><b>IModularClassFile</b></a></td>
	<td>Represents the class file of a module description ("module-info.class").  (Child of <a href=
	"../reference/api/org/eclipse/jdt/core/IPackageFragment.html"><b>IPackageFragment</b></a> )</td>
	</tr>

	<tr>
	<td><a href=
	"../reference/api/org/eclipse/jdt/core/ITypeParameter.html"><b>ITypeParameter</b></a></td>
	<td>Represents a type parameter.  (Not a child of any Java element, it is obtained using
	<a href=
	"../reference/api/org/eclipse/jdt/core/IType.html#getTypeParameter(java.lang.String)"><b>IType.getTypeParameter(String)</b></a>
	or <a href=
	"../reference/api/org/eclipse/jdt/core/IMethod.html#getTypeParameter(java.lang.String)"><b>IMethod.getTypeParameter(String)</b></a>)</td>
	</tr>
	<tr>
	<td><a href=
	"../reference/api/org/eclipse/jdt/core/ILocalVariable.html"><b>ILocalVariable</b></a></td>

	<td>Represents a local variable in a method or an initializer.  (Not a child of any Java
	element, it is obtained using <a href=
	"../reference/api/org/eclipse/jdt/core/ICodeAssist.html#codeSelect(int,%20int)"><b>ICodeAssist.codeSelect(int,
	int)</b></a>)</td>
	</tr>
	<tr>
	<td><a href="../reference/api/org/eclipse/jdt/core/IAnnotation.html"><b>IAnnotation</b></a></td>
	<td>Represents a Java 5 annotation. (Not a child of any Java element, it is obtained using <a href=
	"../reference/api/org/eclipse/jdt/core/IAnnotatable.html#getAnnotation(java.lang.String)"><b>IAnnotatable.getAnnotation(String)</b></a>
	or <a href=
	"../reference/api/org/eclipse/jdt/core/IAnnotatable.html#getAnnotations()"><b>IAnnotatable.getAnnotations()</b></a>)</td>

	</tr>
	<tr>
	<td><a href="../reference/api/org/eclipse/jdt/core/IAnnotatable.html"><b>IAnnotatable</b></a></td>
	<td>Represents a type, a field, a method, a local variable, or a package declaration that can be
	annotated with one or several <a href=
	"../reference/api/org/eclipse/jdt/core/IAnnotation.html"><b>IAnnotation</b></a>s.</td>
	</tr>
	</tbody>
	</table>
	<p>All Java elements support the <a href=
	"../reference/api/org/eclipse/jdt/core/IJavaElement.html"><b>IJavaElement</b></a> interface.</p>
	<p>Some of the elements are shown in the Packages view.  These elements implement the

	<b><a href="../reference/api/org/eclipse/jdt/core/IOpenable.html">IOpenable</a></b> interface,
	since they must be opened before they can be navigated. The figure below shows how these elements
	are represented in the Packages view.</p>
	<p><img src="images/openables.png" border="0" alt=
	"Packages View showing elements implementing the IOpenable interface" /></p>
	<p>The Java elements that implement <b><a href=
	"../reference/api/org/eclipse/jdt/core/IOpenable.html">IOpenable</a></b> are created primarily from
	information found in the underlying resource files.  The same elements are represented
	generically in the resource navigator view.</p>
	<p><img src="images/javanavigator.png" border="0" alt=
	"Resource Navigator showing elements implementing the IOpenable interface" /></p>
	<p>Since 3.3, <b><a href="../reference/api/org/eclipse/jdt/core/IOpenable.html">IOpenable</a></b>s
	that are the root of <b><a href="../reference/api/org/eclipse/jdt/core/IType.html">IType</a></b>s
	implement <b><a href="../reference/api/org/eclipse/jdt/core/ITypeRoot.html">ITypeRoot</a></b> .
	These are <b><a href=
	"../reference/api/org/eclipse/jdt/core/ICompilationUnit.html">ICompilationUnit</a></b> and

	<b><a href="../reference/api/org/eclipse/jdt/core/IClassFile.html">IClassFile</a></b>.</p>
	<p>Other elements correspond to the items that make up a Java compilation unit. The figure below
	shows a Java compilation unit and a content outliner that displays the source elements in the
	compilation unit.</p>
	<img src="images/sourceelements.png" border="0" alt=
	"An editor and a content outliner illustrating the relation between corresponding source elements" />
	<p>These elements implement the <a href=
	"../reference/api/org/eclipse/jdt/core/ISourceReference.html"><b>ISourceReference</b></a>
	interface, since they can provide corresponding source code. (As these elements are selected in the
	content outliner, their corresponding source code is shown in the Java editor).</p>
	<h3>Java elements and their resources</h3>
	<p>Many of the Java elements correspond to generic resources in the workspace.  When you want
	to create Java elements from a generic resource the class <a href=
	"../reference/api/org/eclipse/jdt/core/JavaCore.html"><b>JavaCore</b></a> is the best starting
	point. The following code snippet shows how to get Java elements from their corresponding
	resources.</p>

	<pre class="color1">

	private void createJavaElementsFrom(IProject myProject, IFolder myFolder, IFile myFile) {
	IJavaProject myJavaProject= JavaCore.create(myProject);
	if (myJavaProject == null)
	// the project is not configured for Java (has no Java nature)
	return;

	// get a package fragment or package fragment root
	IJavaElement myPackageFragment= JavaCore.create(myFolder);

	// get a .java (compilation unit), .class (class file), or
	// .jar (package fragment root)
	IJavaElement myJavaFile = JavaCore.create(myFile);
	}
	</pre>
	<p>Once you have a Java element, you can use the JDT API to traverse and query the model.  You
	may also query the non-Java resources contained in a Java element. </p>
	<pre class="color1">
	private void createJavaElementsFrom(IProject myProject, IFolder myFolder, IFile myFile) throws JavaModelException {
	...
	// get the non Java resources contained in my project.
	Object[] nonJavaChildren = myJavaProject.getNonJavaResources();
	...
	}
	</pre>
	<h3>Java projects</h3>
	<p>When you create a Java project from a simple project, <a href=
	"../reference/api/org/eclipse/jdt/core/JavaCore.html"><b>JavaCore</b></a> will check to see if the
	project is configured with the Java nature.  The JDT plug-in uses a project nature to
	designate a project as having Java behavior.  This nature
	(<b>org.eclipse.jdt.core.JavaCore#NATURE_ID</b> ) is assigned to a project when the "New Java
	project" wizard creates a project.  If the Java nature is not configured on a project,

	<a href="../reference/api/org/eclipse/jdt/core/JavaCore.html"><b>JavaCore</b></a> will return null
	when asked to create the project.</p>
	<p><a href="../reference/api/org/eclipse/jdt/core/JavaCore.html"><b>JavaCore</b></a> is also used
	to maintain the Java class path, including locations for finding source code and libraries, and
	locations for generating output binary (<b>.class</b>) files.</p>
	<p>What are the unique characteristics of Java projects? They record their classpath in a
	"<b>.classpath</b>" file and add the Java incremental project builder to the project's build
	spec.  Otherwise, they are just regular projects and can be configured with other natures (and
	other incremental builders) by plug-ins. Plug-ins that want to configure projects with Java
	behavior in addition to their own behavior typically use the <b><a href=
	"../reference/api/org/eclipse/jdt/ui/wizards/NewJavaProjectWizardPage.html">NewJavaProjectWizardPage</a></b>

	to assign the Java nature to the project in addition to their own custom natures or behavior.</p>
	<p><a href="../reference/api/org/eclipse/jdt/core/IJavaModel.html"><b>IJavaModel</b></a> can be
	considered the parent of all projects in the workspace that have the Java project nature (and
	therefore can be treated as an <a href=
	"../reference/api/org/eclipse/jdt/core/IJavaProject.html"><b>IJavaProject</b></a>).</p>
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