ant string manipulation : extracting characters from a string

Question

I have an ant property which has value of the type 1.0.0.123

I want to extract the value after the last dot, in this case that would be '123'. Which ant task should i use and how?

Answer 1

With native ant task

If not wanting to use external libs nor scripting, I found in an answer to a similar question the best option (credit him for this answer). Here you'll be using a ReplaceRegex:

<loadresource property="index">
  <propertyresource name="build.number"/>
  <filterchain>
    <tokenfilter>
      <filetokenizer/>
      <replaceregex pattern=".*\.)" replace="" />
    </tokenfilter>
  </filterchain>
</loadresource>

^{(I have used the same variable names as you in your solution. Of course, this is still missing the increment part of your answer, but that was not in your question.)}

This script loads in index the result of deleting the regex .*\.) from build.number, that is, if build.number = 1.0.0.123 then index = 123.

---

Example

build.xml:

<project name="ParseBuildNumber" default="parse" basedir=".">
    <property name="build.number" value="1.0.0.123"/>

    <target name="parse">
        <loadresource property="index">
            <propertyresource name="build.number"/>
            <filterchain>
                <tokenfilter>
                    <filetokenizer/>
                    <replaceregex pattern=".*\." replace="" />
                </tokenfilter>
            </filterchain>
        </loadresource> 
        <echo message="build.number=${build.number}; index=${index}"/>
    </target>

</project>

$ ant
Buildfile: /tmp/build.xml

parse:
     [echo] build.number=1.0.0.123; index=123

BUILD SUCCESSFUL
Total time: 0 seconds

Answer 2

I suspect the easiest approach may be to use the ant-contrib PropertyRegex task.

Something like this - completely untested:

<propertyregex property="output"
          input="input"
          regexp=".*([^\.]*)"
          select="\1" />