Java interactive input EOF

Question

I'm trying to implement a user input interface for a board game. I'm trying to get user input one at a time and then writing it to a file (since I need to save the list of moves made by the user). What I have so far, works well (reading input and writing it to file), however, whenever the user wants to stop inputting, the program just stops working. I.E; when you press ctrl+c, the program just ends.

Here is what I have so far, the fileName variable has been declared outside the main function

public static void main(String[] args) throws IOException { BufferedReader inputReader = new BufferedReader (new InputStreamReader (System.in)); try { FileWriter outFile = new FileWriter (fileName); PrintWriter out = new PrintWriter (outFile); System.out.print ("Enter move: "); String line = inputReader.readLine(); while (line != null) { System.out.print ("Enter move: "); out.write(inputReader.readLine()); out.write(" "); } out.close(); } catch (IOException e) { System.out.println (e.getMessage()); } System.out.println ("Reached here"); }

What I'm trying to do is whenever the user wants to stop inputting, I want to get to the print line where it says "Reached here". I want to do this because once outside of the loop, I can read the file and then split the input and maniplate it. I remember whilst programming in C, there used to be while (input != EOF); where whenever the user entered ctrl+d or ctrl+c, it stops whatever it is doing and then moves onto the next line of code. How can I do this in java?

Many thanks.

Control-C will terminate your application

Dimitar
– Dimitar

2011-05-10 00:46:09 +00:00
Commented May 10, 2011 at 0:46 — Dimitar
– Dimitar, Commented May 10, 2011 at 0:46

MeBigFatGuy · Accepted Answer · 2011-05-10 00:43:58Z

If you flush after each write, you should at least get a complete file when the user hits control-c.

As for processing more information after control-c happens, you can do that by using a shutdown hook such as:

Runtime.getRuntime().addShutdownHook(new Thread() { public void run() { // do something before quiting } });

however, i don't know that you can cancel the termination.

I would choose a more normal character input for the 'no more input' action.

Dimitar · Accepted Answer · 2011-05-10 00:50:01Z

You can catch the Ctrl+C signal using a SignalHandler. Although I wouldn't recommend this as it would make it difficult for the user to exit your application. Instead you could stop input when the user enters nothing, or use a different command signal.

Thanks, I've changed the interface to inputting a command to stop the input.

Jérôme Verstrynge · Accepted Answer · 2011-05-10 00:48:14Z

You need to agree with a command indicating that user is done (for example "EOF") and add the following in your while loop:

 while (line != null) { System.out.print ("Enter move: "); String r = inputReader.readLine(); if ( r != null ) { if ( "EOF".equals(r) ) break; } out.write(); out.write(" "); }

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