include::sample[dir="snippets/files/copy/groovy",files="build.gradle[tags=filter-files]"]
====

The `filter()` method has two variants, which behave differently:

* one takes a `{javaApi}/java/io/FilterReader.html[FilterReader]` and is designed to work with Ant filters, such as `ReplaceTokens`
* one takes a closure or link:{javadocPath}/org/gradle/api/Transformer.html[Transformer] that defines the transformation for each line of the source file

            task copy(type: Copy) {
                from 'files'
                into 'dest'
                filter(SubstitutingFilter)
            }

            class SubstitutingFilter extends FilterReader {
                SubstitutingFilter(Reader reader) {
                    super(new StringReader(reader.text.replaceAll("one", "1").replaceAll("two", "2")))
                }
            }
        """