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See the License for the specific language governing permissions and limitations under the License. --> <html lang="en"> <head> <link rel="stylesheet" type="text/css" href="../stylesheets/style.css"> <title>Javac Task</title> </head> <body> <h2 id="javac">Javac</h2> <h3>Description</h3> <p>Compiles a Java source tree.</p> <p>The source and destination directory will be recursively scanned for Java source files to compile. Only <code>.java</code> files that have no corresponding <samp>.class</samp> file or where the <code>.class</code> file is older than the <samp>.java</samp> file will be compiled.</p> <p><strong>Note</strong>: Apache Ant uses only the names of the source and class files to find the classes that need a rebuild. It will not scan the source and therefore will have no knowledge about nested classes, classes that are named differently from the source file, and so on. See the <a href="../Tasks/depend.html"><code><depend></code></a> task for dependency checking based on other than just existence/modification times.</p> <p>When the source files are part of a package, the directory structure of the source tree should follow the package hierarchy.</p> <p>It is possible to refine the set of files that are being compiled. This can be done with the <var>includes</var>, <var>includesfile</var>, <var>excludes</var>, and <var>excludesfile</var> attributes. With the <var>includes</var> or <var>includesfile</var> attribute, you specify the files you want to have included. The <var>exclude</var> or <var>excludesfile</var> attribute is used to specify the files you want to have excluded. In both cases, the list of files can be specified by either the filename, relative to the directory(s) specified in the <var>srcdir</var> attribute or nested <code><src></code> element(s), or by using wildcard patterns. See the section on <a href="../dirtasks.html#directorybasedtasks">directory-based tasks</a>, for information on how the inclusion/exclusion of files works, and how to write wildcard patterns.</p> <p id="compilervalues">It is possible to use different compilers. This can be specified by either setting the global <code>build.compiler</code> property, which will affect all <code><javac></code> tasks throughout the build, by setting the <var>compiler</var> attribute, specific to the current <code><javac></code> task or by using a nested element of any <a href="typedef.html">typedef</a>fed or <a href="componentdef.html">componentdef</a>fed type that implements <code>org.apache.tools.ant.taskdefs.compilers.CompilerAdapter</code>. Valid values for either the <code>build.compiler</code> property or the <var>compiler</var> attribute are:</p> <ul> <li><q>classic</q> (the standard compiler of JDK 1.1/1.2) – <q>javac1.1</q> and <q>javac1.2</q> can be used as aliases.</li> <li><q>modern</q> (the standard compiler of JDK 1.3 and later) – <q>javac1.3</q>, <q>javac1.4</q>, <q>javac1.5</q> and <q>javac1.6</q>, <q>javac1.7</q> (<em>since Ant 1.8.2</em>), <q>javac1.8</q> (<em>since Ant 1.8.3</em>), <q>javac1.9</q> (<em>since Ant 1.9.5</em>), <q>javac9</q> (<em>since Ant 1.9.8</em>) and <q>javac10+</q> (<em>since Ant 1.10.2</em>) can be used as aliases.</li> <li><q>jikes</q> (the <a href="http://jikes.sourceforge.net/" target="_top">Jikes</a> compiler).</li> <li><q>jvc</q> (the Command-Line Compiler from Microsoft's SDK for Java / Visual J++) – <q>microsoft</q> can be used as an alias.</li> <li><q>kjc</q> (the <a href="https://web.archive.org/web/20050212025507/http://www.dms.at/kopi/index.html" target="_top">kopi</a> compiler).</li> <li><q>gcj</q> (the <code>gcj</code> compiler from <a href="https://gcc.gnu.org/gcc-7/changes.html#java" target="_top">GCC</a>).</li> <li><q>sj</q> (Symantec Java compiler) – <q>symantec</q> can be used as an alias.</li> <li><q>extJavac</q> (run either modern or classic in a JVM of its own).</li> </ul> <p>The default is <q>javac1.x</q> with <q>x</q> depending on the JDK version you use while you are running Ant. If you wish to use a different compiler interface than those supplied, you can write a class that implements the CompilerAdapter interface (package <code>org.apache.tools.ant.taskdefs.compilers</code>). Supply the full classname in the <code>build.compiler</code> property or the <var>compiler</var> attribute.</p> <p>The <var>fork</var> attribute overrides the <code>build.compiler</code> property or <var>compiler</var> attribute setting and expects a JDK 1.1 or higher to be set in <code>JAVA_HOME</code>.</p> <p>You can also use the <var>compiler</var> attribute to tell Ant which JDK version it shall assume when it puts together the command line switches—even if you set <var>fork</var>=<q>true</q>. This is useful if you want to run the compiler of JDK 1.1 while your current JDK is 1.2+. If you use <var>compiler</var>=<q>javac1.1</q> and (for example) <var>depend</var>=<q>true</q>, Ant will use the command line switch <kbd>-depend</kbd> instead of <kbd>-Xdepend</kbd>.</p> <p>This task will drop all entries that point to non-existent files/directories from the classpath it passes to the compiler.</p> <p>The working directory for a forked executable (if any) is the project's base directory.</p> <p><strong>Windows Note</strong>: When the modern compiler is used in unforked mode on Windows, it locks up the files present in the classpath of the <code><javac></code> task, and does not release them. The side effect of this is that you will not be able to delete or move those files later on in the build. The workaround is to fork when invoking the compiler.</p> <p>If you are using Java 8 or above and your source contains native methods or fields annotated with the <code>@Native</code> annotation you can set the <var>nativeheaderdir</var> attribute in order to use the <kbd>-h</kbd> switch of <kbd>javac</kbd> to generate the native header files. Note that the logic Ant uses to determine which files to compile does not take native headers into account, i.e. if the <samp>.class</samp> is more recent than the corresponding <samp>.java</samp> file the file will not get compiled even if a native header file generated for it would be outdated.</p> <h3>Parameters</h3> <table class="attr"> <tr> <th scope="col">Attribute</th> <th scope="col">Description</th> <th scope="col">Required</th> </tr> <tr> <td>srcdir</td> <td>Location of the java files. (See the <a href="#srcdirnote">note</a> below.)</td> <td>Yes, unless nested <code><src></code> elements or <var>modulesourcepath</var> attribute or corresponding elements are present</td> </tr> <tr> <td>destdir</td> <td>Location to store the class files.</td> <td>No</td> </tr> <tr> <td>includes</td> <td>Comma- or space-separated list of patterns of files that must be included.</td> <td>No; defaults to all <samp>.java</samp> files</td> </tr> <tr> <td>includesfile</td> <td>Name of a file. Each line of this file is taken to be an include pattern.</td> <td>No</td> </tr> <tr> <td>excludes</td> <td>Comma- or space-separated list of patterns of files that must be excluded.</td> <td>No; defaults to default excludes or none if <var>defaultexcludes</var> is <q>no</q></td> </tr> <tr> <td>excludesfile</td> <td>Name of a file. Each line of this file is taken to be an exclude pattern.</td> <td>No</td> </tr> <tr> <td>defaultexcludes</td> <td>Indicates whether default excludes should be used or not (<q>yes|no</q>).</td> <td>No; defaults to <q>yes</q></td> </tr> <tr> <td>classpath</td> <td>The classpath to use.</td> <td>No</td> </tr> <tr> <td>sourcepath</td> <td>The sourcepath to use. To suppress the <code>sourcepath</code> switch, use <var>sourcepath</var>=<q></q>.</td> <td>No; defaults to <var>srcdir</var> unless nested <code><src></code> elements are specified</td> </tr> <tr> <td>bootclasspath</td> <td>Location of bootstrap class files. (See <a href="#bootstrap">below</a> for using the <kbd>-X</kbd> and <kbd>-J-X</kbd> parameters for specifying the bootstrap classpath).</td> <td>No</td> </tr> <tr> <td>classpathref</td> <td>The <var>classpath</var> to use, given as a <a href="../using.html#references">reference</a> to a path defined elsewhere.</td> <td>No</td> </tr> <tr> <td>sourcepathref</td> <td>The <var>sourcepath</var> to use, given as a <a href="../using.html#references">reference</a> to a path defined elsewhere.</td> <td>No</td> </tr> <tr> <td>bootclasspathref</td> <td>The <var>bootstrapclasspath</var> to use, given as a <a href="../using.html#references">reference</a> to a path defined elsewhere.</td> <td>No</td> </tr> <tr> <td>extdirs</td> <td>Location of installed extensions.</td> <td>No</td> </tr> <tr> <td>encoding</td> <td>Encoding of source files. (<strong>Note</strong>: <code>gcj</code> doesn't support this option yet.)</td> <td>No</td> </tr> <tr> <td>nowarn</td> <td>Indicates whether the <kbd>-nowarn</kbd> switch should be passed to the compiler.</td> <td>No; defaults to <q>off</q></td> </tr> <tr> <td>debug</td> <td>Indicates whether source should be compiled with debug information. If set to <q>off</q>, <kbd>-g:none</kbd> will be passed on the command line for compilers that support it (for other compilers, no command line argument will be used). If set to <q>true</q>, the value of the <var>debuglevel</var> attribute determines the command line argument.</td> <td>No; defaults to <q>off</q></td> </tr> <tr> <td>debuglevel</td> <td>Keyword list to be appended to the <kbd>-g</kbd> command-line switch. Legal values are <q>none</q> or a comma-separated list of the following keywords: <q>lines</q>, <q>vars</q>, and <q>source</q>.</td> <td>No; ignored when <var>debug</var> is <q>false</q> or any implementation other than <q>modern</q>, <q>javac1.2</q> and <q>jikes</q>; by default, nothing will be appended to <kbd>-g</kbd></td> </tr> <tr> <td>optimize</td> <td>Indicates whether source should be compiled with optimization. <strong>Note</strong> that this flag is just ignored by Sun's <kbd>javac</kbd> since JDK 1.3 (because compile-time optimization is unnecessary).</td> <td>No; defaults to <q>off</q></td> </tr> <tr> <td>deprecation</td> <td>Indicates whether source should be compiled with deprecation information.</td> <td>No; defaults to <code>off</code></td> </tr> <tr> <td>verbose</td> <td>Asks the compiler for verbose output.</td> <td>No; defaults to <q>no</q></td> </tr> <tr> <td>depend</td> <td>Enables dependency tracking for compilers that support this (<q>jikes</q> and <q>classic</q>).</td> <td>No</td> </tr> <tr> <td>includeAntRuntime</td> <td>Whether to include the Ant run-time libraries in the classpath. <em>It is usually best</em> to set this to <q>false</q> so the script's behavior is not sensitive to the environment in which it is run.</td> <td>No; defaults to <q>yes</q>, unless <a href="../sysclasspath.html"><code>build.sysclasspath</code></a> property is set</td> </tr> <tr> <td>includeJavaRuntime</td> <td>Whether to include the default run-time libraries from the executing JVM in the classpath.<br/><strong>Note</strong>: In some setups the run-time libraries may be part of the "Ant run-time libraries" so you may need to explicitly set <var>includeAntRuntime</var> to <q>false</q> to ensure that the Java run-time libraries are not included.</td> <td>No; defaults to <q>no</q></td> </tr> <tr> <td>fork</td> <td>Whether to execute <code>javac</code> using the JDK compiler externally.</td> <td>No; defaults to <q>no</q></td> </tr> <tr> <td>executable</td> <td>Complete path to the <kbd>javac</kbd> executable to use in case of <var>fork</var> is <q>yes</q>.<br/><em>Since Ant 1.6</em> this attribute can also be used to specify the path to the executable when using <q>jikes</q>, <q>jvc</q>, <q>gcj</q> or <q>sj</q>.</td> <td>No; defaults to the compiler of current JDK, ignored if <var>fork</var> is <q>no</q></td> </tr> <tr> <td>memoryInitialSize</td> <td>The initial size of the memory for the underlying JVM, if <kbd>javac</kbd> is run externally. (Examples: <q>83886080</q>, <q>81920k</q>, or <q>80m</q>)</td> <td>No; defaults to the standard JVM memory setting, ignored if <var>fork</var> is <q>no</q></td> </tr> <tr> <td>memoryMaximumSize</td> <td>The maximum size of the memory for the underlying JVM, if <kbd>javac</kbd> is run externally; ignored otherwise. (Examples: <q>83886080</q>, <q>81920k</q>, or <q>80m</q>)</td> <td>No; defaults to the standard JVM memory setting, ignored if <var>fork</var> is <q>no</q></td> </tr> <tr> <td>failonerror</td> <td>Indicates whether compilation errors will fail the build>.</td> <td>No; defaults to <q>true</q></td> </tr> <tr> <td>errorProperty</td> <td>The property to set to <q>true</q> if compilation fails. <em>Since Ant 1.7.1</em>.</td> <td>No</td> </tr> <tr> <td>source</td> <td>Java language features accepted by compiler, as specified by the <kbd>-source</kbd> command-line switch. Valid feature versions are <q>1.3</q>, <q>1.4</q>, <q>1.5</q> or <q>5</q>, etc. The attribute will be ignored by all implementations prior to <q>javac1.4</q> (or <q>modern</q> when Ant is not running in a JVM 1.3), <q>gcj</q> and <q>jikes</q>.<br/> If you use this attribute together with <q>gcj</q> or <q>jikes</q>, you must make sure that your version supports the <kbd>-source</kbd> (or <kbd>-fsource</kbd> for <kbd>gcj</kbd>) switch.</td> <td>No; by default, no <kbd>-source</kbd> argument will be used at all unless the magic <a href="../javacprops.html#source"><code>ant.build.javac.source</code></a> property is set<br/><strong>Note that the default value depends on JDK that is running Ant. We highly recommend to always specify this attribute.</strong></td> </tr> <tr> <td>target</td> <td>Generate class files for specific JVM version (cross-compile).</td> <td>No; by default, no <kbd>-target</kbd> argument will be used at all unless the magic <a href="../javacprops.html#target"><code>ant.build.javac.target</code></a> property is set<br/><strong>Note that the default value depends on JDK that is running Ant and on <var>source</var> (see <a href="https://docs.oracle.com/javase/8/docs/technotes/tools/windows/javac.html#BHCJDCID" target="_top">Cross-Compilation Options</a>). We highly recommend to always specify this attribute.</strong></td> </tr> <tr> <td>compiler</td> <td>The compiler implementation to use. See the above <a href="#compilervalues">list</a> of valid compilers.</td> <td>No; defaults to the value of the <code>build.compiler</code> property, if set, or default compiler for the current JDK otherwise</td> </tr> <tr> <td>listfiles</td> <td>Indicates whether the source files to be compiled will be listed.</td> <td>No; defaults to <q>no</q></td> </tr> <tr> <td>tempdir</td> <td>Where Ant should place temporary files. This is only used if the task is forked and the command line args length exceeds 4 kB. <em>Since Ant 1.6</em>.</td> <td>No; default is <code>java.io.tmpdir</code></td> </tr> <tr> <td>updatedProperty</td> <td>The property to set to <q>true</q> if compilation has taken place and has been successful. <em>Since Ant 1.7.1</em>.</td> <td>No</td> </tr> <tr> <td>includeDestClasses</td> <td>This attribute controls whether to include the destination classes directory in the classpath given to the compiler. If set to <q>true</q> (default), previously compiled classes are on the classpath for the compiler. This means that "greedy" compilers will not recompile dependent classes that are already compiled. In general this is a good thing as it stops the compiler for doing unnecessary work. However, for some edge cases, involving generics, the <kbd>javac</kbd> compiler needs to compile the dependent classes to get the generics information. One example is documented in the bug report: <a href="https://issues.apache.org/bugzilla/show_bug.cgi?id=40776" target="_top">Bug 40776 - a problem compiling a Java 5 project with generics</a>. Setting the attribute to <q>false</q> will cause the compiler to recompile dependent classes. <em>Since Ant 1.7.1</em>.</td> <td>No; default is <q>true</q></td> </tr> <tr> <td>createMissingPackageInfoClass</td> <td>Some package level annotations in <samp>package-info.java</samp> files don't create any <samp>package-info.class</samp> files so Ant would recompile the same file every time.<br/><em>Since Ant 1.8</em>, an empty <samp>package-info.class</samp> is created for each <samp>package-info.java</samp> if there isn't one created by the compiler.<br/>In some setups this additional class causes problems and it can be suppressed by setting this attribute to <q>false</q>. <em>Since Ant 1.8.3</em>.</td> <td>No; default is <q>true</q></td> </tr> <tr> <td>modulepath</td> <td>Specify where to find application modules. A list of directories of modules, module files or exploded modules. <em>since Ant 1.9.7</em></td> <td>No</td> </tr> <tr> <td>modulepathref</td> <td>The <var>modulepath</var> to use, given as <a href="../using.html#references">reference</a> to a path defined elsewhere. <em>since Ant 1.9.7</em></td> <td>No</td> </tr> <tr> <td>modulesourcepath</td> <td>Specify where to find input source files for multiple module compilation. <em>since Ant 1.9.7</em></td> <td>Yes, unless <var>srcdir</var> attribute or nested <code><src></code> elements are present</td> </tr> <tr> <td>modulesourcepathref</td> <td>The <var>modulesourcepath</var> to use, given as <a href="../using.html#references">reference</a> to a path defined elsewhere. <em>since Ant 1.9.7</em></td> <td>No</td> </tr> <tr> <td>upgrademodulepath</td> <td>Specify the location of modules that replace upgradeable modules in the runtime image. <em>since Ant 1.9.7</em></td> <td>No</td> </tr> <tr> <td>upgrademodulepathref</td> <td>The <var>upgrademodulepath</var> to use, given as <a href="../using.html#references">reference</a> to a path defined elsewhere. <em>since Ant 1.9.7</em></td> <td>No</td> </tr> <tr> <td>nativeheaderdir</td> <td>Specify where to place generated native header files. <em>Since Ant 1.9.8</em>. <td>No, ignored when running on JDK 7 or earlier</td> </tr> <tr> <td>release</td> <td>Specify the value for the <kbd>--release</kbd> switch.<br/>When set and running on JDK 9+ the <var>source</var> and <var>target</var> attributes as well as the <var>bootclasspath</var> will be ignored. <em>Since Ant 1.9.8</em>. <td>No, ignored when running on JDK 8 or earlier</td> </tr> </table> <h3>Parameters specified as nested elements</h3> <p>This task forms an implicit <a href="../Types/fileset.html">FileSet</a> and supports most attributes of <code><fileset></code> (<var>dir</var> becomes <var>srcdir</var>) as well as the nested <code><include></code>, <code><exclude></code> and <code><patternset></code> elements.</p> <h4><code>srcdir</code>, <code>classpath</code>, <code>sourcepath</code>, <code>bootclasspath</code>, <code>modulepath</code>, <code>modulesourcepath</code>, <code>upgrademodulepath</code> and <code>extdirs</code></h4> <p><code><javac></code>'s <var>srcdir</var>, <var>classpath</var>, <var>sourcepath</var>, <var>bootclasspath</var>, <var>extdirs</var>, <var>modulepath</var>, <var>modulesourcepath</var>, and <var>upgrademodulepath</var> attributes are <a href="../using.html#path">path-like structures</a> and can also be set via nested <code><src></code> (note the different name!), <code><classpath></code>, <code><sourcepath></code>, <code><bootclasspath></code>, <code><extdirs></code>, <code><modulepath></code>, <code><modulesourcepath></code> and <code><upgrademodulepath></code> elements, respectively.</p> <h4>compilerarg</h4> <p>You can specify additional command line arguments for the compiler with nested <code><compilerarg></code> elements. These elements are specified like <a href="../using.html#arg">Command-line Arguments</a> but have an additional attribute that can be used to enable arguments only if a given compiler implementation will be used.</p> <table class="attr"> <tr> <th scope="col">Attribute</th> <th scope="col">Description</th> <th scope="col">Required</th> </tr> <tr> <td>value</td> <td rowspan="4">See <a href="../using.html#arg">Command-line Arguments</a>.</td> <td rowspan="4">Exactly one of these</td> </tr> <tr> <td class="var">line</td> </tr> <tr> <td class="var">file</td> </tr> <tr> <td class="var">path</td> </tr> <tr> <td>prefix</td> <td rowspan="2">See <a href="../using.html#arg">Command-line Arguments</a>. <em>Since Ant 1.8</em>.</td> <td>No</td> </tr> <tr> <td>suffix</td> <td>No</td> </tr> <tr> <td>compiler</td> <td>Only pass the specified argument if the chosen compiler implementation matches the value of this attribute. Legal values are the same as those in the above <a href="#compilervalues">list</a> of valid compilers.)</td> <td>No</td> </tr> </table> <h4>compilerclasspath</h4> <p><em>Since Ant 1.8.0</em></p> <p>A <a href="../using.html#path">path-like structure</a> holding the classpath to use when loading the compiler implementation if a custom class has been specified. Doesn't have any effect when using one of the built-in compilers.</p> <h4>Any nested element of a type that implements <code>CompilerAdapter</code></h4> <p><em>Since Ant 1.8.0</em></p> <p>If a defined type implements the <code>CompilerAdapter</code> interface a nested element of that type can be used as an alternative to the <var>compiler</var> attribute.</p> <h3>Examples</h3> <p>Compile all <samp>.java</samp> files under the <samp>${src}</samp> directory, and store the <samp>.class</samp> files in the <samp>${build}</samp> directory. The classpath used includes <samp>xyz.jar</samp>, and compiling with debug information is on. The source level is <q>1.4</q>, so you can use <code>assert</code> statements.</p> <pre> <javac srcdir="${src}" destdir="${build}" classpath="xyz.jar" debug="on" source="1.4"/></pre> <p>Compile all <samp>.java</samp> files under the <samp>${src}</samp> directory, and store the <samp>.class</samp> files in the <samp>${build}</samp> directory. Java compiler is forked using the default <kbd>javac</kbd> executable. The source level is <q>1.2</q> (similar to <q>1.1</q> or <q>1.3</q>) and the class files should be runnable under JDK 1.2+ as well.</p> <pre> <javac srcdir="${src}" destdir="${build}" fork="true" source="1.2" target="1.2"/></pre> <p>Compile all <samp>.java</samp> files under the <samp>${src}</samp> directory, and store the <samp>.class</samp> files in the <samp>${build}</samp> directory. Java compiler is forked using the executable named <kbd>java$javac.exe</kbd>. Note that the <q>$</q> sign needs to be escaped by a second one. The source level is <q>1.5</q>, so you can use generics.</p> <pre> <javac srcdir="${src}" destdir="${build}" fork="java$$javac.exe" source="1.5"/></pre> <p>Compile <samp>.java</samp> files under the <samp>${src}</samp> directory, and store the <samp>.class</samp> files in the <code>${build}</code> directory. The classpath used includes <samp>xyz.jar</samp>, and debug information is on. Only files under <samp>mypackage/p1</samp> and <samp>mypackage/p2</samp> are used. All files in and below the <samp>mypackage/p1/testpackage</samp> directory are excluded from compilation. You didn't specify a source or target level, so the actual values used will depend on which JDK you ran Ant with.</p> <pre> <javac srcdir="${src}" destdir="${build}" includes="mypackage/p1/**,mypackage/p2/**" excludes="mypackage/p1/testpackage/**" classpath="xyz.jar" debug="on"/></pre> <p>This is the same as the previous example, with the addition of a second source path, defined by the property <samp>src2</samp>. This can also be represented using nested <code><src></code> elements as follows:</p> <pre> <javac destdir="${build}" classpath="xyz.jar" debug="on"> <src path="${src}"/> <src path="${src2}"/> <include name="mypackage/p1/**"/> <include name="mypackage/p2/**"/> <exclude name="mypackage/p1/testpackage/**"/> </javac></pre> <p>If you want to run the <kbd>javac</kbd> compiler of a different JDK, you should tell Ant where to find the compiler and which version of JDK you will be using so it can choose the correct command line switches. The following example executes a JDK 1.1 <kbd>javac</kbd> in a new process and uses the correct command line switches even when Ant is running in a JVM of a different version:</p> <pre> <javac srcdir="${src}" destdir="${build}" fork="yes" executable="/opt/java/jdk1.1/bin/javac" compiler="javac1.1"/></pre> <p id="srcdirnote"><strong>Note</strong>: If you wish to compile only source files located in certain packages below a common root, use the <var>include</var>/<var>exclude</var> attributes or <code><include></code>/<code><exclude></code> nested elements to filter for these packages. Do not include part of your package structure in the <var>srcdir</var> attribute (or nested <code><src></code> elements), or Ant will recompile your source files every time you run your compile target. See the <a href="https://ant.apache.org/faq.html#always-recompiles" target="_top">Ant FAQ</a> for additional information.</p> <p>If you wish to compile only files explicitly specified and disable <code>javac</code>'s default searching mechanism then you can unset the <var>sourcepath</var> attribute:</p> <pre> <javac sourcepath="" srcdir="${src}" destdir="${build}" > <include name="**/*.java"/> <exclude name="**/Example.java"/> </javac></pre> <p>That way the <code>javac</code> will compile all Java source files under <samp>${src}</samp> directory but skip the examples. The compiler will even produce errors if some of the non-example files refers to them.</p> <p>If you wish to compile with a special JDK (another than the one Ant is currently using), set the <var>executable</var> and <var>fork</var> attribute. Using <var>taskname</var> could show in the log, that these settings are fix.</p> <pre> <javac srcdir="" destdir="" executable="path-to-java14-home/bin/javac" fork="true" taskname="javac1.4"/></pre> <p><strong>Note</strong>: If you are using Ant on Windows and a new DOS window pops up for every use of an external compiler, this may be a problem of the JDK you are using. This problem may occur with all JDKs prior to 1.2.</p> <p>If you want to activate other compiler options like <code>lint</code> you could use the <code><compilerarg></code> element:</p> <pre> <javac srcdir="${src.dir}" destdir="${classes.dir}" classpathref="libraries"> <compilerarg value="-Xlint"/> </javac></pre> <p>If you want to use a custom CompilerAdapter <code>org.example.MyAdapter</code> you can either use the <var>compiler</var> attribute:</p> <pre> <javac srcdir="${src.dir}" destdir="${classes.dir}" compiler="org.example.MyAdapter"/></pre> <p>or a define a type and nest this into the task like in:</p> <pre> <componentdef classname="org.example.MyAdapter" name="myadapter"/> <javac srcdir="${src.dir}" destdir="${classes.dir}"> <myadapter/> </javac></pre> <p>in which case your compiler adapter can support attributes and nested elements of its own.</p> <p>The following examples demonstrate the use of Java 9+ modules.</p> <p>Compile all <samp>.java</samp> files in a single module under the <samp>${src}</samp> directory, and store the <samp>.class</samp> files in the <code>${build}</code> directory. The compilation uses application modules located in <samp>modules</samp> folder. The source level is <q>9</q> to enable modules.</p> <pre> <javac srcdir="${src}" destdir="${build}" includeantruntime="false" modulepath="modules" source="9"/></pre> <p>Compile all <samp>.java</samp> files in <samp>gen/classes</samp>, <samp>lin32/classes</samp> and <code>lin64/classes</code> in all source modules under the <code>${src}</code> directory. Generate module directories in the <samp>${build}</samp> directory. Each generated module directory under the <samp>${build}</samp> directory contains <code>.class</code> files from corresponding source module. The <samp>*</samp> is a token representing the name of any of the modules in the compilation module set. The <code>{ ... , ... }</code> express alternates for expansion. The compilation uses application modules located in <code>modules</code> folder. The source level is <q>9</q> to enable modules.</p> <pre> <javac modulesourcepath="${src}/*/{gen,lin{32,64}}/classes" destdir="${build}" includeantruntime="false" modulepath="modules" source="9"/></pre> <h3 id="jikes">Jikes notes</h3> <p>You need Jikes 1.15 or later.</p> <p>Jikes supports some extra options, which can be set be defining the properties shown below prior to invoking the task. The setting for each property will be in effect for all <code><javac></code> tasks throughout the build. The Ant developers are aware that this is ugly and inflexible – expect a better solution in the future. All the options are boolean, and must be set to <q>true</q> or <q>yes</q> to be interpreted as anything other than <q>false</q>. By default, <code>build.compiler.warnings</code> is <q>true</q>, while all others are <q>false</q>.</p> <table> <tr> <th scope="col">Property</th> <th scope="col">Description</th> <th scope="col">Default</th> </tr> <tr> <td><code>build.compiler.emacs</code></td> <td>Enable emacs-compatible error messages.</td> <td><q>false</q></td> </tr> <tr> <td><code>build.compiler.fulldepend</code></td> <td>Enable full dependency checking; see<br/> the <code>+F</code> switch in the Jikes manual.</td> <td><q>false</q></td> </tr> <tr> <td><code>build.compiler.pedantic</code></td> <td>Enable pedantic warnings.</td> <td><q>false</q></td> </tr> <tr> <td><code>build.compiler.warnings</code><br/><em><u>Deprecated</u></em>. Use <code><javac></code>'s <var>nowarn</var> attribute instead.</td> <td>Don't disable warning messages.</td> <td><q>true</q></td> </tr> </table> <h3 id="jvc">Jvc notes</h3> <p><q>Jvc</q> will enable Microsoft extensions unless you set the property <code>build.compiler.jvc.extensions</code> to <q>false</q> before invoking <code><javac></code>.</p> <h3 id="bootstrap">Bootstrap options</h3> <p>The Sun <kbd>javac</kbd> compiler has a <kbd>-bootclasspath</kbd> command line option—this corresponds to the <var>bootclasspath</var> attribute/element of the <code><javac></code> task. The Sun compiler also allows more control over the boot classpath using the <kbd>-X</kbd> and <kbd>-J-X</kbd> attributes. One can set these by using the <code><compilerarg></code>. <em>Since Ant 1.6.0</em>, there is a shortcut to convert path references to strings that can by used in an OS independent fashion (see <a href="../using.html#pathshortcut">pathshortcut</a>). For example:</p> <pre> <path id="lib.path.ref"> <fileset dir="lib" includes="*.jar"/> </path> <javac srcdir="src" destdir="classes"> <compilerarg arg="-Xbootclasspath/p:${toString:lib.path.ref}"/> </javac></pre> <h3>OpenJDK notes</h3> <p>The <a href="https://openjdk.java.net/" target="_top">OpenJDK</a> project has provided the <code>javac</code> <a href="https://openjdk.java.net/groups/compiler/" target="_top">compiler</a> as an open source project. The output of this project is a <code>javac.jar</code> which contains the <kbd>javac</kbd> compiler. This compiler may be used with the <code><javac></code> task with the use of a <kbd>-Xbootclasspath/p</kbd> Java argument. The argument needs to be given to the runtime system of the <kbd>javac</kbd> executable, so it needs to be prepended with a <kbd>-J</kbd>, for example:</p> <pre> <property name="patched.javac.jar" location="${my.patched.compiler}/dist/lib/javac.jar"/> <presetdef name="patched.javac"> <javac fork="yes"> <compilerarg value="-J-Xbootclasspath/p:${patched.javac.jar}"/> </javac> </presetdef> <patched.javac srcdir="src/java" destdir="build/classes" debug="yes"/></pre> <h3>Note on package-info.java</h3> <p><samp>package-info.java</samp> files were introduced in Java 5 to allow package level annotations. On compilation, if the <code>.java</code> file does not contain runtime annotations, there will be no corresponding <code>.class</code> file. Prior to Ant 1.7.1, when the <code><javac></code> task is run again, the task will try to compile the <samp>package-info.java</samp> files again.</p> <p>With Ant 1.7.1, a different kind of logic was introduced that involved the timestamp of the directory that would normally contain the <samp>.class</samp> file. This logic turned out to lead to Ant not recompiling <samp>package-info.java</samp> in certain setup.</p> <p><em>Since Ant 1.8.0</em>, an "empty" <samp>package-info.class</samp> file is created if Ant compiles a <samp>package-info.java</samp> and no <samp>package-info.class</samp> file has been created by the compiler itself.</p> </body> </html>