Use epoch time to change file's time-stamp using java

Question

I am working on a java application running on linux machine, that should change a file's time-stamp to another time which is stored in form of epoch. The file whose time-stamp needs to be changed is present in local file system.

Ex - localFile.txt whose timestamp shows 17 Jul 5 20:03 needs to be changed to epoch "1341446400000"

I have written code like this -

private void modifyTime(final String localFile, final long originalEpoch) throws  IOException {
    String getDateFromEpoch = "date -d@" + String.valueOf(originalEpoch);
    //getDateFromEpoch is returned in form - "Thu Jul  5 20:03:32 UTC 2012"
    Process process = runCommand(getDateFromEpoch);
    InputStream iStream = process.getInputStream();
    BufferedReader bufReader = new BufferedReader(new InputStreamReader(iStream));
    String originalDate = bufReader.readLine();
    bufReader.close();

    String touch = "touch -c -d " + originalDate + " " + localFile;
    runCommand(touch);
}

private Process runCommand(final String cmd) throws IOException {
    Process p = Runtime.getRuntime().exec(cmd);
    try {
        p.waitFor();
    } catch (InterruptedException e) {
        // ignore this exception
    }
    return p;
}

Running "date -d@" + String.valueOf(originalEpoch); is returning something like Thu Jul 5 20:03:32 UTC 2012. Using this in touch command is not working for me.

Is there a way of doing this?

Answer 1

Sounds like you just want File.setLastModified

http://docs.oracle.com/javase/7/docs/api/java/io/File.html#setLastModified(long)