Question

I am trying to check the ant build script’s argument is set or not. I have tried many way to do this but there is no success. I define the argument with -Dmaindir="../propertyfolderpath".

Here is the code sample that I have tried;

<ac:if>
    <equals arg1="@{maindir}" arg2="" />
    <ac:then>
        <echo message="maindir argument is empty. Current properties will be used." />
        <property file="build.properties" />
    </ac:then>
    <ac:else>
        <echo message="maindir = ${maindir}" />
        <ac:if>
            <ac:available file="${maindir}/build.properties" type="file" />
            <ac:then>
                <property file="${maindir}/build.properties" />
            </ac:then>
            <ac:else>
                <fail message="${maindir} is not a valid path." />
            </ac:else>
        </ac:if>
    </ac:else>  
</ac:if>

• There are three cases;
  1. Argument might not be defined. Ant should go into first
  2. Argument defined well.
  3. Argument defined with wrong path

For 2nd case script is working.
For 3rd case script is working.
But for 1st case, I mean when I dont define maindir argument, ant act like 3rd case. That is my problem.

Why ant act like that?

Answer 1

Maybe you can try setting a default value for the argument?

<condition property="maindir" value="[default]">
    <not>  
        <isset property="maindir"/>
    </not>
</condition>
<echo message="${maindir}" />

I tried this and it works, when no argument is passed the value of ${maindir} is [default].