hasNextLine() while loop not exiting

Question

I understand that I need to use hasNextLine() to advance the line - but when i made a reference to hasNextLine(), I'm not sure why it is still not exiting the while loop:

I'm using a scanner here (sc) to read an input file

while(sc.hasNextLine()){                            
//read post specifications from line
                            String postspecs = sc.nextLine();

                            //split line
                            String[] postspecs_s = postspecs.split(", ");


                            //create post
                            reddit.findUser(stripExtension(argfile.getName())).
                            addPost(postspecs_s[0], PostType.valueOf
                                    (postspecs_s[1]), postspecs_s[2]);

                            System.out.println("created");
                        }

it is reading a txt file line to line and storing elements of that file into an array of string. then i use the elements of the array of string to create an object as seen in the last couple of lines. in the end i print created (just so i know how many times it went through the while loop) — Joy Kuo
– Joy Kuo, Commented Feb 16, 2015 at 2:23
I know what it's supposed to do. Since you said it doesn't work, I assume it doesn't do that. What does it do? — Stack Exchange Broke The Law
– Stack Exchange Broke The Law, Commented Feb 16, 2015 at 2:25
its not exiting the while loop - which means it continues to print created endlessly. — Joy Kuo
– Joy Kuo, Commented Feb 16, 2015 at 2:27

Jean-François Savard · Accepted Answer · 2015-02-16 01:47:54Z

1

´hasNextLine´ will only return false if EOF (end of file) char is reached. An easier way to stop reading is to wait for a sentinel value it you are reading from System.in.

So you would have a something like

String s = sc.nextLine();
while(!s.equals(SENTINEL))
    //proceed and dont forget to re-read.

I think ctrl+z will send EOF to system.in on Windows, on iPod atm so can't test.

answered Feb 16, 2015 at 1:47

Jean-François Savard

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