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From: Steven Simpson <ss@domain.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: [Windows] Any way to distinguish ^C Induced EOF from ^Z EOF?
Date: Tue, 13 Mar 2012 17:26:27 +0000
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On 13/03/12 13:11, Jan Burse wrote:
> Its a custom made wrapper for Signal & SignalHandler.
> In version 1 of the above class I used the package
> sun.misc.*. In version 2 of the above class I
> used reflection i.e. Proxy class etc.. It will
> noop when sun.misc.Signal is not present.

I was going to suggest using Runtime.addShutdownHook(Thread) as a 
portable alternative.  You don't find out which signal was raised, but 
it gives your program a chance to shut down gracefully instead of abruptly.

import java.io.*;

public class TestInput {
     public static void main(String[] args) throws Exception {
         Runtime.getRuntime().addShutdownHook(new Thread() {
                 public void run() {
                     try {
                         Thread.sleep(10 * 1000);
                     } catch (InterruptedException ex) {
                     }
                 }
             });

         FileInputStream fs = new FileInputStream(FileDescriptor.in);
         byte[] buf = new byte[256];
         for (;;) {
             System.out.print("test: ");
             int len = fs.read(buf);
             String str = new String(buf,0,Math.max(0,len));
             System.out.println("len = "+len+", buf = "+str+", buf[0]="+buf[0]);
             if ("exit".equals(str.trim())) break;
         }
     }
}

Unfortunately, you still get the same read()==-1 on Windows, while the 
read call doesn't return on Linux.  Of course, this loop doesn't 
terminate on EOF, and while the shutdown hook is still running, you can 
continue to type on both Windows and Linux, and have the results printed.

However, this could be a way to distinguish the 'fake' EOF from a real 
one.  Having received -1, read again.  A real one will produce -1 again, 
but the fake one will block or yield more input.  For a real EOF, the 
behaviour seems the same on Windows and Linux, so stop when you get two 
'-1's.  Can't speak for Mac, or anything else, of course.

Is a read() call's behaviour well defined after a previous call returned 
-1?  I couldn't tell from a quick scan of the docs.

-- 
ss at comp dot lancs dot ac dot uk