Reading a file while it is being written

Question

Overview

• Topic 1 Trying to write some data to a file continuously
• Topic 2 Trying to continuously read from a single file for analysis and data processing (read-only)

Problem:

• In thread 2, the file size remains constant (this is not updated since Thread 1 is trying to write data to the file), and therefore I cannot parse the size of the original file.

Proven Things

• A FileInputStream: . I tried to read from the input stream, the file size remains unchanged (122924 bytes) and never increases
• RandomAccessFile: Same result as above, file size remains constant (122924 bytes), r / rw modes checked
• FileChannel: I tried to work with the channel from FileInputStream, the same result as above

Answer 1

You need to lock when you write or read a file. Thus, only one thread can access the file.

Here is the official Android site explaining the lock:

http://developer.android.com/reference/java/util/concurrent/locks/Lock.html

Here is an example of using a lock:

fooobar.com/questions/1541732 / ...

You can also use synchronization to lock the object, here it is explained:

Java sync