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I have 2-3 programs which can modify file but I want to block others if one program is using it. I cant use synchronization in this. Is there any other provision ?

Kalrav J Parsana
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  • Do you actually mean different programs, or different threads in the same program? – khelwood Nov 24 '16 at 10:17
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    Does this work for you? http://stackoverflow.com/questions/128038/how-can-i-lock-a-file-using-java-if-possible – Jaydee Nov 24 '16 at 10:18
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    @Jaydee's suggestion is what I'd normally use. However, the documentation says: "Whether or not a lock actually prevents another program from accessing the content of the locked region is system-dependent and therefore unspecified." Make sure this is not a problem for you. – Nando Nov 24 '16 at 10:21

1 Answers1

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The file locking over different application it isn't at Java level handled. You must handle it at OS level. Different OS has different solutions.

I want to block others if one program is using it.

Probably you want to have a write lock, excluding all readers and writers. But allowing some of your programs. At windows maybe present this link interest.

It is very platform dependent, but is a Java code to try it:

FileInputStream in = new FileInputStream(file);
try {
    java.nio.channels.FileLock lock = in.getChannel().lock();
    try {
        Reader reader = new InputStreamReader(in, charset);
        ...
    } finally {
        lock.release();
    }
} finally {
    in.close();
}
matheszabi
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