使用RandomAccessFile检查空位置

Question

I need to check if a position in a random access file has not been written to. The problem with this is, when the position actually hasn't been written to, I get (as anticipated) an EOFException. I have been reading RandomAccessFile documentation to try to solve this problem, and tried researching online.

Things I've tried:

• Using a try-catch block and catching every time there is a EOFException (Using try-catch as a conditional statement). It works, but it is horrible practice, and it is very inefficient, as for my case it is EOF the majority of the time.

• Using a BufferReader to loop through and check the position. I ended up running into many problems and decided that there must be a better way.

I don't want to do any copying one file over to another or any other work around. I know there has to be a direct way of doing this, I just can't seem to find the correct solution.

Answer 1

Are you trying to write a "tailer"?

What you need to do is have one thread which reads only the data which is there using FileChannel.size() to check for more data. This data is passed to a piped input. This allows you to have a second thread which reads the piped stream continuously eg using BufferedReader and blocks where more data is needed.