Use pure Ant to implement if else condition (check command line input)

Question

I am a newbie in Ant. My ant script receives a user input variable named \"env\" from command line:

e.g. ant doIt -Denv=test

Th

Answer 1

You can create few targets and use if/unless tags.

<project name="if.test" default="doIt">

    <target name="doIt" depends="-doIt.init, -test, -prod, -dev, -else"></target>

    <target name="-doIt.init">
        <condition property="do.test">
            <equals arg1="${env}" arg2="test" />
        </condition>
        <condition property="do.prod">
            <equals arg1="${env}" arg2="prod" />
        </condition>
        <condition property="do.dev">
            <equals arg1="${env}" arg2="dev" />
        </condition>
        <condition property="do.else">
            <not>
                <or>
                <equals arg1="${env}" arg2="test" />
                <equals arg1="${env}" arg2="prod" />
                <equals arg1="${env}" arg2="dev" />
                </or>
            </not>
        </condition>
    </target>

    <target name="-test" if="do.test">
        <echo>this target will be called only when property $${do.test} is set</echo>
    </target>

    <target name="-prod" if="do.prod">
        <echo>this target will be called only when property $${do.prod} is set</echo>
    </target>

    <target name="-dev" if="do.dev">
        <echo>this target will be called only when property $${do.dev} is set</echo>
    </target>

    <target name="-else" if="do.else">
        <echo>this target will be called only when property $${env} does not equal test/prod/dev</echo>
    </target>

</project>

Targets with - prefix are private so user won't be able to run them from command line.

Answer 2

If any of you require a plain if/else condition (without elseif); then use the below:

Here I am dependent on a env variable DMAPM_BUILD_VER, but it may happen that this variable is not set in the env. So I need to have mechanism to default to a local value.

    <!-- Read build.version value from env variable DMAPM_BUILD_VER. If it is not set, take default.build.version. -->
    <property name="default.build.version" value="0.1.0.0" />
    <condition property="build.version" value="${env.DMAPM_BUILD_VER}" else="${default.build.version}">
        <isset property="env.DMAPM_BUILD_VER"/>
    </condition>