Since Apache Ant 1.6.3
Display or set a property containing length information for a string, a file, or one or more
nested resource collections.  Can also be used as
a condition.
| Attribute | Description | Required | |
|---|---|---|---|
| Task | Condition | ||
| property | The property to set. | No; by default, output value to the log | Ignored | 
| mode | File length mode; when allthe resulting value is the sum of all included resources' lengths; when eachthe task outputs the absolute path and length of each included resource, one per line. | No; default is all | |
| file | Single file whose length to report. | One of these, or one or more nested filesets | |
| resource | Single resource whose length to report (using extended properties handling). Since Ant 1.8.1 | ||
| string | The string whose length to report. | ||
| trim | Whether to trim when operating on a string. | No; default is false, ignored unless string is set | |
| length | Comparison length. | Ignored | Yes | 
| when | Comparison
      type: equal, eq, greater, gt, less, lt, ge(greater or equal), ne(not equal), le(less or equal). | No; default is equal | |
You can include resources via nested resource collections.
Store the length of the string foo
 in the property named length.foo.
<length string="foo" property="length.foo"/>
Store the length of file bar in the property named length.bar.
<length file="bar" property="length.bar"/>
Store the file paths of foo and bar and their length into the
property length.
<length property="length" mode="each">
    <fileset dir="." includes="foo,bar"/>
</length>
Add the length of foo and bar and store the result in
property length.
<length property="length" mode="all">
    <fileset dir="." includes="foo,bar"/>
</length>