Enhance the build file

Enhance the build file

Now we have a working buildfile we could do some enhancements: many time you are referencing the same directories, main-class and jar-name are hard coded, and while invocation you have to remember the right order of build steps.

The first and second point would be addressed with properties, the third with a special property - an attribute of the <project>-tag and the fourth problem can be solved using dependencies.

<project name="HelloWorld" basedir="." default="main">
<property name="src.dir"     value="src"/>
<property name="build.dir"   value="build"/>
<property name="classes.dir" value="build/classes"/>
<property name="jar.dir"     value="build/jar"/>
<property name="main-class"  value="oata.HelloWorld"/>
<target name="clean">
<delete dir="build"/>
</target>
<target name="compile">
<mkdir dir="${classes.dir}"/>
<javac srcdir="src" destdir="${classes.dir}"/>
</target>
<target name="jar" depends="compile">
<mkdir dir="${jar.dir}"/>
<jar destfile="${jar.dir}/apache-ant.jar" basedir="${classes.dir}">
<manifest>
<attribute name="Main-Class" value="${main-class}"/>
</manifest>
</jar>
</target>
<target name="run" depends="jar">
<java jar="${jar.dir}/apache-ant.jar" fork="true"/>
</target>
<target name="clean-build" depends="clean,jar"/>
<target name="main" depends="clean,run"/>
</project>

Now it's easier, just do a ant and you will get

Buildfile: build.xml
clean:
compile:
[mkdir] Created dir: C:\...\build\classes
[javac] Compiling 1 source file to C:\...\build\classes
jar:
[mkdir] Created dir: C:\...\build\jar
[jar] Building jar: C:\...\build\jar\HelloWorld.jar
run:
[java] Hello World
main:
BUILD SUCCESSFUL