How to append data to a file?

Question

I trying to write into the txt file.
But with out losing the data that is already stored in the file.

But my problem that when I put string in the txt file, the

Answer 1

In Java 7,

Files.write(FileSystems.getDefault().getPath(targetDir,fileName),
strContent.getBytes(),StandardOpenOption.CREATE,StandardOpenOption.APPEND);