Append data into a file using Apache Commons I/O

It has been implemented in 2.1 version of Apache IO.
To append string to the file just pass true as an additional parameter in functions:

• FileUtils.writeStringToFile
• FileUtils.openOutputStream
• FileUtils.write
• FileUtils.writeByteArrayToFile
• FileUtils.writeLines

ex:

    FileUtils.writeStringToFile(file, "String to append", true);