Question

So I’m a Java-newbie and started some playing with files. Say I have some file “tes.t” containing data of a type known for me – assume they’re int-double-int-double and so forth. I don’t know the amount of such pairs inside, though – how can I make sure the input has finished? For my current knowledge, I thought of something like this:

try{
        DataInputStream reading = new DataInputStream(new FileInputStream("tes.t"));
        while(true)
        {
            System.out.println(reading.readInt());
            System.out.println(reading.readDouble());
        }
        }catch(IOException xxx){}
}

However, this infinite loop here makes me somehow uncomfortable. I mean – I guess the IOException should catch on as soon as the input has finished but I’m not sure if that’s a good way to go. Is there any better way to do this? Or rather – what is a better approach as I’m sure mine is bad 🙂

Answer 1

Since your file has int-double pair, You can do that as following:

DataInputStream dis = null;
try {
    dis = new DataInputStream(new FileInputStream("tes.t"));
    int i = -1;
    // readInt() returns -1 if end of file...
    while ((i=dis.readInt()) != -1) {
        System.out.println(i);
        // since int is read, it must have double also..
        System.out.println(dis.readDouble());
    }

} catch (EOFException e) {
    // do nothing, EOF reached

} catch (IOException e) {
    // handle it

} finally {
    if (dis != null) {
        try {
            dis.close();

        } catch (IOException e) {
             // handle it
        }
    }
}