Question

can anyone explain why the author does not close the stream LineNumberReader lnr? Is this not necessary?

protected static ArrayList<Mount> getMounts() throws Exception{
    LineNumberReader lnr = null;
    lnr = new LineNumberReader(new FileReader("/proc/mounts"));
    String line;
    ArrayList<Mount> mounts = new ArrayList<Mount>();
    while ((line = lnr.readLine()) != null)
    {  
        RootTools.log(line);

        String[] fields = line.split(" ");
        mounts.add(new Mount(new File(fields[0]), // device
            new File(fields[1]), // mountPoint
            fields[2], // fstype
            fields[3] // flags
        ));
    }
    InternalVariables.mounts = mounts;

    if (InternalVariables.mounts != null) {
        return InternalVariables.mounts;
    } else {
        throw new Exception();
    }
}

Moreover, in previous versions was:

finally {
    //no need to do anything here.
}

source code

Is this a mistake or specifics?

Answer 1

It’s technically not necessary since the object will be deleted by the GC when it goes out of scope, and the teardown process could close it. It’s considered a good practice to close any I/O streams you open, just to make sure.