Apache ant creating jar files

Creating JAR files is a common task in Java development, and Apache Ant provides several built-in tasks that make it easy to create JAR files as part of a build process.

Here's an example of how to use the built-in Ant "jar" task to create a JAR file:

<target name="jar">
  <jar destfile="${dist.dir}/myproject.jar">
    <fileset dir="${build.dir}">
      <include name="**/*.class"/>
      <include name="**/*.properties"/>
    </fileset>
    <manifest>
      <attribute name="Main-Class" value="com.example.myproject.Main"/>
    </manifest>
  </jar>
</target>

In this example, the "jar" task is defined as a target called "jar". The "destfile" attribute specifies the name and location of the output JAR file. The "fileset" element specifies which files to include in the JAR file, using Ant file patterns. The "manifest" element specifies the contents of the JAR file's manifest file, including the main class to be executed when the JAR file is run.

To run the "jar" target, simply run the Ant command with the "jar" target:

ant jar

This will create a JAR file in the specified location, including the compiled class files and any other files specified in the "fileset" element.

Note that the "jar" task supports many other options and attributes, such as including/excluding certain files, setting the compression level, and adding security attributes. For more information, see the Apache Ant documentation on the "jar" task.