Future<RandomAccessFile> open({FileMode mode: FileMode.READ})

Open the file for random access operations. Returns a Future<RandomAccessFile> that completes with the opened random access file. RandomAccessFiles must be closed using the RandomAccessFile.close method.

Files can be opened in three modes:

FileMode.READ: open the file for reading.

FileMode.WRITE: open the file for both reading and writing and truncate the file to length zero. If the file does not exist the file is created.

FileMode.APPEND: same as FileMode.WRITE except that the file is not truncated.

Source 

Future<RandomAccessFile> open({FileMode mode: FileMode.READ});