Fail

Description

Exits the current build (just throwing a BuildException), optionally printing additional information.

The message of the Exception can be set via the message attribute or character data nested into the element.

Parameters

Attribute	Description	Required
message	A message giving further information on why the build exited	No
if	Only fail if a property of the given name exists in the current project	No
unless	Only fail if a property of the given name doesn't exist in the current project	No
status	Exit using the specified status code; assuming the generated Exception is not caught, the JVM will exit with this status. Since Apache Ant 1.6.2	No

Parameters specified as nested elements

As an alternative to the if/unless attributes, conditional failure can be achieved using a single nested <condition> element, which should contain exactly one core or custom condition. For information about conditions, see here.
Since Ant 1.6.2

Examples

  <fail/>

will exit the current build with no further information given.

BUILD FAILED

build.xml:4: No message

  <fail message="Something wrong here."/>

will exit the current build and print something like the following to wherever your output goes:

BUILD FAILED

build.xml:4: Something wrong here.

  <fail>Something wrong here.</fail>

will give the same result as above.

  <fail unless="thisdoesnotexist"/>

will exit the current build and print something like the following to wherever your output goes:

BUILD FAILED

build.xml:2: unless=thisdoesnotexist

Using a condition to achieve the same effect:

  <fail>
     <condition>
       <not>
         <isset property="thisdoesnotexist"/>
       </not>
     </condition>
   </fail>

Output:

BUILD FAILED

build.xml:2: condition satisfied

<fail message="Files are missing.">
    <condition>
        <not>
            <resourcecount count="2">
                <fileset id="fs" dir="." includes="one.txt,two.txt"/>
            </resourcecount>
        </not>
    </condition>
</fail>

Will check that both files one.txt and two.txt are present otherwise the build will fail.