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| <title>Compiling Java code</title> |
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| <h2>Compiling Java code</h2> |
| <p> See the |
| Java development user guide for <a href="PLUGINS_ROOT/org.eclipse.jdt.doc.user/tasks/task-using_batch_compiler.htm">using the batch compiler</a> and |
| <a href="PLUGINS_ROOT/org.eclipse.jdt.doc.user/tasks/task-ant_javac_adapter.htm">using the ant javac adapter</a>.</p> |
| |
| <p>The JDT plug-ins include an incremental and batch Java compiler for building Java .class files from source code. There is no direct API provided by the compiler. It is installed as a builder on |
| Java projects. Compilation is triggered using standard platform build mechanisms.</p> |
| |
| <p>The platform build mechanism is described in detail in <a href="../../org.eclipse.platform.doc.isv/guide/resAdv_builders.htm" class="XRef">Incremental project builders</a>.</p> |
| <h3>Compiling code</h3> |
| <p>You can programmatically compile the Java source files in a project using the build API.</p> |
| <pre class="color1"> |
| |
| IProject myProject; |
| IProgressMonitor myProgressMonitor; |
| myProject.build(IncrementalProjectBuilder.INCREMENTAL_BUILD, myProgressMonitor); |
| </pre> |
| <p>For a Java project, this invokes the Java incremental project builder (along with any other incremental project builders that have been added to the project's build spec). The generated .class |
| files are written to the designated output folder. Additional resource files are also copied to the output folder. </p> |
| <p>In the case of a full batch build, all the .class files in the output folder may be 'scrubbed' to ensure that no stale files are found. This is controlled using a JDT Core Builder Option (<a href= |
| "../reference/api/org/eclipse/jdt/core/JavaCore.html#CORE_JAVA_BUILD_CLEAN_OUTPUT_FOLDER">CORE_JAVA_BUILD_CLEAN_OUTPUT_FOLDER</a>). The default for this option is to clean output folders. |
| |
| Unless this option is reset, you must ensure that you place all .class files for which you do not have corresponding source files in a separate class file folder on the classpath instead of the |
| output folder.</p> |
| <p>The incremental and batch builders can be configured with other options that control which resources are copied to the output folder. The following sample shows how to set up a resource |
| filter so that files ending with '.ignore' and folders named 'META-INF', are not copied to the output folder:</p> |
| <pre class="color1"> |
| |
| Hashtable options = JavaCore.getOptions(); |
| options.put(JavaCore.CORE_JAVA_BUILD_RESOURCE_COPY_FILTER, "*.ignore,META-INF/"); |
| JavaCore.setOptions(options); |
| </pre> |
| <p>Filenames are filtered out if they match one of the supplied patterns. Entire folders are filtered out if their name matches one of the supplied folder names which end in a path separator.</p> |
| <p>The incremental and batch builders can also be configured to only generate a single error when the .classpath file has errors. This option is set by default and eliminates numerous errors. |
| See <a href="jdt_api_options.htm#builder">JDT Core Builder Options</a> for a complete list of builder-related options and their defaults.</p> |
| |
| <p>The compiler can also be configured using <a href="../reference/api/org/eclipse/jdt/core/JavaCore.html"><b>JavaCore</b></a> options. For example, you can define the severity that should be |
| used for different kinds of problems that are found during compilation. See <a href="jdt_api_options.htm#compiler">JDT Core Compiler Options</a> for a complete list of compiler-related options |
| and their defaults.</p> |
| <p>When programmatically configuring options for the builder or compiler, you should specify the scope of the option. For example, setting up a resource filter may apply to a particular project |
| only:</p> |
| <pre> |
| |
| <span class="c2"> |
| Hashtable options = myProject.getOptions(false); // get only the options set up in this project |
| options.put(JavaCore.CORE_JAVA_BUILD_RESOURCE_COPY_FILTER, "*.ignore,META-INF/"); |
| myProject.setOptions(options); |
| </span> |
| </pre> |
| <h3>Problem determination</h3> |
| |
| <p>JDT Core defines a specialized marker (marker type "<b>org.eclipse.jdt.core.problem</b> ") to denote compilation problems. To programmatically discover problems detected by the compiler, the |
| standard platform marker protocol should be used. See <a href="../../org.eclipse.platform.doc.isv/guide/resAdv_markers.htm" class="XRef">Resource Markers</a> for an overview of using markers.</p> |
| <p>The following snippet finds all Java problem markers in a compilation unit.</p> |
| <pre> |
| <span class="c2"> |
| public IMarker[] findJavaProblemMarkers(ICompilationUnit cu) |
| throws CoreException { |
| IResource javaSourceFile = cu.getUnderlyingResource(); |
| IMarker[] markers = |
| javaSourceFile.findMarkers(IJavaModelMarker.JAVA_MODEL_PROBLEM_MARKER, |
| true, IResource.DEPTH_INFINITE); |
| } |
| </span> |
| </pre> |
| <p>Java problem markers are maintained by the Java project builder and are removed automatically as problems are resolved and the Java source is recompiled.</p> |
| |
| <p>The problem id value is set to one of the constants defined in <b><a href="../reference/api/org/eclipse/jdt/core/compiler/IProblem.html">IProblem</a></b> . The problem's id is reliable, but the |
| message is localized and therefore can be changed according to the default locale. The constants defined in <b><a href="../reference/api/org/eclipse/jdt/core/compiler/IProblem.html">IProblem</a></b> |
| are self-descriptive.</p> |
| <p>An implementation of <b><a href="../reference/api/org/eclipse/jdt/core/IProblemRequestor.html">IProblemRequestor</a></b> should be defined to collect the problems discovered during a Java |
| operation. Working copies can be reconciled with problem detection if a <b><a href="../reference/api/org/eclipse/jdt/core/IProblemRequestor.html">IProblemRequestor</a></b> has been supplied for the |
| working copy creation. To achieve this, you can use the <b><a href= |
| "../reference/api/org/eclipse/jdt/core/ICompilationUnit.html#reconcile(int,%20boolean,%20org.eclipse.jdt.core.WorkingCopyOwner,%20org.eclipse.core.runtime.IProgressMonitor)">reconcile</a></b> method. |
| Here is an example:</p> |
| |
| <pre class="color1"> |
| |
| ICompilationUnit unit = ..; // get some compilation unit |
| |
| // create requestor for accumulating discovered problems |
| IProblemRequestor problemRequestor = new IProblemRequestor() { |
| public void acceptProblem(IProblem problem) { |
| System.out.println(problem.getID() + ": " + problem.getMessage()); |
| } |
| public void beginReporting() {} |
| public void endReporting() {} |
| public boolean isActive() { return true; } // will detect problems if active |
| }; |
| |
| // use working copy to hold source with error |
| ICompilationUnit workingCopy = unit.getWorkingCopy(new WorkingCopyOwner() {}, problemRequestor, null); |
| ((IOpenable)workingCopy).getBuffer().setContents("public class X extends Zork {}"); |
| |
| // trigger reconciliation |
| workingCopy.reconcile(NO_AST, true, null, null); |
| </pre> |
| <p>You can add an action on the reported problems in the acceptProblem(IProblem) method. In this example, the reported problem will be that <b>Zork cannot be resolved or is not a valid superclass</b> |
| and its id is <b>IProblem.SuperclassNotFound</b>.</p> |
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