Ant if else condition?

Question

Is there an if/else condition that I can use for an Ant task?

This is what i have written so far:

Answer 1

Since ant 1.9.1 you can use a if:set condition : https://ant.apache.org/manual/ifunless.html

Answer 2

You can also do this with ant contrib's if task.

<if>
    <equals arg1="${condition}" arg2="true"/>
    <then>
        <copy file="${some.dir}/file" todir="${another.dir}"/>
    </then>
    <elseif>
        <equals arg1="${condition}" arg2="false"/>
        <then>
            <copy file="${some.dir}/differentFile" todir="${another.dir}"/>
        </then>
    </elseif>
    <else>
        <echo message="Condition was neither true nor false"/>
    </else>
</if>

Answer 3

The quirky syntax using conditions on the target (described by Mads) is the only supported way to perform conditional execution in core ANT.

ANT is not a programming language and when things get complicated I choose to embed a script within my build as follows:

<target name="prepare-copy" description="copy file based on condition">
    <groovy>
        if (properties["some.condition"] == "true") {
            ant.copy(file:"${properties["some.dir"]}/true", todir:".")
        }
    </groovy>
</target>

ANT supports several languages (See script task), my preference is Groovy because of it's terse syntax and because it plays so well with the build.

Apologies, David I am not a fan of ant-contrib.

Answer 4

<project name="Build" basedir="." default="clean">
    <property name="default.build.type" value ="Release"/>

    <target name="clean">
    <echo>Value Buld is now  ${PARAM_BUILD_TYPE} is set</echo>
        <condition property="build.type" value="${PARAM_BUILD_TYPE}" else="${default.build.type}">
            <isset property="PARAM_BUILD_TYPE"/>
        </condition>

       <echo>Value Buld is now  ${PARAM_BUILD_TYPE} is set</echo>
       <echo>Value Buld is now  ${build.type} is set</echo>
    </target>
</project>

In my Case DPARAM_BUILD_TYPE=Debug if it is supplied than, I need to build for for Debug otherwise i need to go for building Release build. I write like above condition it worked and i have tested as below it is working fine for me.

And property ${build.type} we can pass this to other target or macrodef for processing which i am doing in my other ant macrodef.

D:\>ant -DPARAM_BUILD_TYPE=Debug
Buildfile: D:\build.xml
clean:
     [echo] Value Buld is now  Debug is set
     [echo] Value Buld is now  Debug is set
     [echo] Value Buld is now  Debug is set
main:
BUILD SUCCESSFUL
Total time: 0 seconds
D:\>ant
Buildfile: D:\build.xml
clean:
     [echo] Value Buld is now  ${PARAM_BUILD_TYPE} is set
     [echo] Value Buld is now  ${PARAM_BUILD_TYPE} is set
     [echo] Value Buld is now  Release is set
main:
BUILD SUCCESSFUL
Total time: 0 seconds

It work for me to implement condition so posted hope it will helpful.

Answer 5

The if attribute does not exist for <copy>. It should be applied to the <target>.

Below is an example of how you can use the depends attribute of a target and the if and unless attributes to control execution of dependent targets. Only one of the two should execute.

<target name="prepare-copy" description="copy file based on condition"
    depends="prepare-copy-true, prepare-copy-false">
</target>

<target name="prepare-copy-true" description="copy file based on condition"
    if="copy-condition">
    <echo>Get file based on condition being true</echo>
    <copy file="${some.dir}/true" todir="." />
</target>

<target name="prepare-copy-false" description="copy file based on false condition" 
    unless="copy-condition">
    <echo>Get file based on condition being false</echo>
    <copy file="${some.dir}/false" todir="." />
</target>

If you are using ANT 1.8+, then you can use property expansion and it will evaluate the value of the property to determine the boolean value. So, you could use if="${copy-condition}" instead of if="copy-condition".

In ANT 1.7.1 and earlier, you specify the name of the property. If the property is defined and has any value (even an empty string), then it will evaluate to true.