If you use Apache Commons IO it's a one-liner:
FileUtils.deleteDirectory(dir);
See FileUtils.deleteDirectory()
Guava used to support similar functionality:
Files.deleteRecursively(dir);
This has been removed from Guava several releases ago.
While the above version is very simple, it is also pretty dangerous, as it makes a lot of assumptions without telling you. So while it may be safe in most cases, I prefer the "official way" to do it (since Java 7):
public static void deleteFileOrFolder(final Path path) throws IOException {
Files.walkFileTree(path, new SimpleFileVisitor<Path>(){
@Override public FileVisitResult visitFile(final Path file, final BasicFileAttributes attrs)
throws IOException {
Files.delete(file);
return CONTINUE;
}
@Override public FileVisitResult visitFileFailed(final Path file, final IOException e) {
return handleException(e);
}
private FileVisitResult handleException(final IOException e) {
e.printStackTrace(); // replace with more robust error handling
return TERMINATE;
}
@Override public FileVisitResult postVisitDirectory(final Path dir, final IOException e)
throws IOException {
if(e!=null)return handleException(e);
Files.delete(dir);
return CONTINUE;
}
});
};