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Check Properties


This example illustrates how to check properties using environment variable whether it is set or not. In this code, there are three properties; the first two are used to define source directory and destination directory. The source directory is 'src' and the destination directory is 'build'. The element <property environment="env"> is a path of jar file dependent on environment variables, and these are available only if you use <property environment="env"> before you import the property file. The following example shows how to check whether TOMCAT_HOME environment variable is set or not. If TOMCAT_HOME environment variable is set, then the output will display build successful... as given below.



<project name="Check Properties" default="compile" basedir=".">

  <property name="dir.src" value="src"/>
  <property name="dir.build" value="build"/>
  <property environment="env"/>

  <target name="check">
    <fail unless="env.TOMCAT_HOME">TOMCAT_HOME class path must be set</fail>    

  <target name="clean" depends="check">
    <delete dir="${dir.build}"/>

  <target name="prepare" depends="clean">
    <mkdir dir="${dir.build}"/>

  <target name="compile" depends="prepare" >
    <echo>Compile code...</echo>



But if TOMCAT_HOME environment variable is not set, then the following error message will be displayed.

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