Java read system input in while loop

Question

here is a very simple code, in which i am trying to take input from keyboard in a loop. For every input, the loop is automatically running two extra times and taking the values 13 and 10, no matter what i give as input. can you please point out what i am doing wrong.

CODE:

public static void main(String args[]) { BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); boolean loop_cond=true; int n=1; while(loop_cond==true) { try { System.out.print("input : "); n=br.read(); } catch (IOException e) { e.printStackTrace(); } System.out.print(n+"\n"); } } // end Main

OUTPUT :

input : 6 54 input : 13 input : 10 input : 9 57 input : 13 input : 10 input : 1 49 input : 13 input : 10 input :

13 is a carriage return and 10 is a newline. unixhelp.ed.ac.uk/CGI/man-cgi?ascii+7 — Matt Ball
– Matt Ball, Commented Mar 21, 2013 at 3:59
I believe your program also reads in the "Enter/New line" character — SNpn
– SNpn, Commented Mar 21, 2013 at 4:00
Understood it. But how to prevent this ? i only want to run the loop only once for every input i provide. — Suman.hassan95
– Suman.hassan95, Commented Mar 21, 2013 at 4:02

Sudhanshu Umalkar · Accepted Answer · 2013-03-21 03:59:38Z

1

Those are probably \r\n values. Try Scanner to take in values.

 Scanner input = new Scanner(System.in); int i = input.nextInt();

answered Mar 21, 2013 at 3:59

Sudhanshu Umalkar

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2 Comments

Suman.hassan95 Over a year ago

Thank you very much Sudhanshu. It is working just the way i want. But can you tell me how to implement this in BufferedReader ?

Sudhanshu Umalkar Over a year ago

use readLine() instead of read(). readLine() returns String so you might have to convert it to int.

Jayamohan · Accepted Answer · 2013-03-21 04:08:42Z

Change

n=br.read();

to

n = Integer.parseInt(br.readLine());

But I would recommend you to use Scanner class to avoid the Integer conversion.

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