Sets a property if a target file or set of target files is more up-to-date
than a source file or set of source files. A single source file is specified
using the srcfile attribute. A set of source files is specified
using the nested <srcfiles>
elements. These are FileSets,
whereas multiple target files are specified using a nested
<mapper> element.
By default, the value of the property is set to true if
the timestamp of the source file(s) is not more recent than the timestamp of
the corresponding target file(s). You can set the value to something other
than the default by specifying the value attribute.
If a <srcfiles> element is used, without also specifying
a <mapper> element, the default behavior is to use a
merge mapper, with the
to attribute set to the value of the
targetfile attribute.
Normally, this task is used to set properties that are useful to avoid target execution depending on the relative age of the specified files.
| Attribute | Description | Required |
| property | The name of the property to set. | Yes |
| value | The value to set the property to. | No; defaults to true. |
| srcfile | The file to check against the target file(s). | Yes, unless a nested
<srcfiles> or <srcresources>
element is present. |
| targetfile | The file for which we want to determine the status. | Yes, unless a nested
<mapper> element is present. |
The nested <srcfiles> element is a
fileset and allows you to
specify a set of files to check against the target file(s).
Note: You can specify either the srcfile
attribute or nested <srcfiles> elements, but not both.
Note that the task will completely ignore any directories that seem to be matched by the srcfiles fileset, it will only consider normal files. If you need logic that applies to directories as well, use a nested srcresource and a dirset (for example).
The nested <srcresources> element is a union and allows you to
specify a collection of resources to check against the target file(s).
Since Apache Ant 1.7
The nested <mapper> element allows you to specify
a set of target files to check for being up-to-date with respect to a
set of source files.
The mapper "to" attribute is relative to the target file, or to the "dir" attribute of the nested srcfiles element.
Since Ant 1.6.3, one can use a filenamemapper type in place of the mapper element.
<uptodate property="xmlBuild.notRequired" targetfile="${deploy}\xmlClasses.jar" >
<srcfiles dir= "${src}/xml" includes="**/*.dtd"/>
</uptodate>
sets the property xmlBuild.notRequired to true
if the ${deploy}/xmlClasses.jar file is more up-to-date than
any of the DTD files in the ${src}/xml directory.
This can be written as:
<uptodate property="xmlBuild.notRequired">
<srcfiles dir= "${src}/xml" includes="**/*.dtd"/>
<mapper type="merge" to="${deploy}\xmlClasses.jar"/>
</uptodate>
as well.
The xmlBuild.notRequired property can then be used in a
<target> tag's unless attribute to
conditionally run that target. For example, running the following target:
<target name="xmlBuild" depends="chkXmlBuild" unless="xmlBuild.notRequired"> ... </target>will first run the
chkXmlBuild target, which contains
the <uptodate> task that determines whether
xmlBuild.notRequired gets set. The property named in
the unless attribute is then checked for being set/not set.
If it did get set (ie., the jar file is up-to-date),
then the xmlBuild target won't be run.
The following example shows a single source file being checked against a single target file:
<uptodate property="isUpToDate"
srcfile="/usr/local/bin/testit"
targetfile="${build}/.flagfile"/>
sets the property isUpToDate to true
if /usr/local/bin/testit is not newer than
${build}/.flagfile.
The following shows usage of a relative mapper.
<uptodate property="checkUptodate.uptodate">
<srcfiles dir="src" includes="*"/>
<mapper type="merge" to="../dest/output.done"/>
</uptodate>
<echo message="checkUptodate result: ${checkUptodate.uptodate}"/>
The previous example can be a bit confusing, so it may be better to use absolute paths:
<property name="dest.dir" location="dest"/>
<uptodate property="checkUptodate.uptodate">
<srcfiles dir="src" includes="*"/>
<mapper type="merge" to="${dest.dir}/output.done"/>
</uptodate>