You need to use Commons IO.

To use Commons IO in a Maven 2 project, add the following dependency to your project's pom.xml:

    <dependency>
        <groupId>commons-io</groupId>
        <artifactId>commons-io</artifactId>
        <version>1.4</version>
    </dependency>

If you are not sure what this means, I'd suggest reading Maven: The Definitive Guide. When you depend on a library in Maven 2, all you need to do is add the dependency groupId, artifactId, and version to your project's dependencies. Once you do this, Maven 2 will download the dependency and make it available on your project's classpath.

Commons IO contains a few utilities for simplifying a number of common I/O tasks. CopyUtils and IOUtils in the org.apache.commons.io package provide a suite of static utility methods for working with streams and readers. org.apache.commons.io.FileUtils provides static utility methods to help with common File operations, such as touching a file, recursive deletion of directories, and reading files. The org.apache.commons.io.filefilter package contains implementations of FilenameFilter, such as SuffixFileFilter, which accepts files with a specified name suffix.

For more information about the Commons IO project, see the project page at http://commons.apache.org/io.