How to set memory used by JVM in Ant ?

Example. Set memory used by JVM in Ant

<project name="MemoryMap" default="compile" basedir=".">

  <property name="sourcedir" value="${basedir}/src"/>

  <property name="targetdir" value="${basedir}/build"/>

  <property name="librarydir" value="${basedir}/lib"/>

  <path id="libraries">

    <fileset dir="${librarydir}">

      <include name="*.jar"/>

    </fileset>

  </path>

  <target name="clean">

    <delete dir="${targetdir}"/>

    <delete dir="${librarydir}"/>

  </target>

  <target name="prepare" depends="clean">

    <mkdir dir="${sourcedir}"/>

    <mkdir dir="${targetdir}"/>

    <mkdir dir="${librarydir}"/>

  </target>

  <target name="compile" depends="prepare">

    <javac srcdir="${sourcedir}" destdir="${targetdir}" debug="true" 

     fork="true" memoryMaximumSize="1024m" memoryInitialSize="256m">

    </javac>       

  </target>    

</project>

In this example,

<property name="sourcedir"> is used to specify the location of source directory

<propertyname="targetdir"> is used to specify the location of target directory

<property name="librarydir"> is used to define the location of library directory

<path id="libraries"> is used to put any jar file in the lib directory

The target <targetname="clean"> is used to delete the target directory and library directory from base directory.

The target <targetname="prepare"> is used to create the source directory, target directory and library directory.

<target name="compile"> is used to compile the source code.

fork="true" is used if you don't run Java code in a separate JVM to the ant script, you can get some pretty strange errors that are difficult to diagnose. 

For NoClassDefFoundError, the problem was fixed by setting fork=true in the java target.

 

The memoryMaximumSize="1024m" for the underlying VM, if using fork mode; ignored otherwise.

Defaults to the standard VM memory setting. (Examples: 83886080, 81920k, or 80m)

memoryInitialSize="256m" is used for the underlying VM, if using fork mode; ignored otherwise.

Defaults to the standard VM memory setting. (Examples: 83886080, 81920k, or 80m).