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Thread: Help With Scanner

  1. #1
    Junior Member
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    Default Help With Scanner

    I trust I'm posting this in the right forum. You nice people do consider 3 semesters of java still "new," right??

    Anyway, I'm having a problem with Scanner. I have my program prompting me for a file name, and when I type in a file name and hit enter, the program does not seem like it's going to the next step. Now, when I step through in debug mode, it looks like it's making it to a few lines down, where I start scanning the file and counting the number of lines. But my lines variable goes waaaaay past the true number of lines in the file.

    Anyway, what I don't understand, mainly, is why my program seems to get stuck. Is it because it's counting the lines? Also, why does it keep incrementing? My file has 10 lines...

    Here's my code:

      public static void main(String[] args)
      {
        String filename; 
    	 int lines = 0;
        Scanner input_scan = new Scanner(System.in),
    	         file_scan;
     
        System.out.print("Enter a file name: ");
    	 filename = input_scan.next();
     
    	 file_scan = new Scanner(filename);
    	 while (file_scan.hasNextLine())
    	   lines++;

    Here is everything in the text file I'm scanning:

    1234 23 widget1
    3456 123 widget2
    4356 45 widget3
    1056 1234 widget4
    9999 237 widget5
    9322 22 widget6
    5322 755 widget7
    3422 2 widget8
    3333 95 widget9
    1111 15 widget10

    That's it.

    Any help would be greatly appreciated!


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: Help With Scanner

    the hasNext method in Scanner doesn't actually move the Scanner to read the next line. You have to manually do it.

    while(file_scan.hasNext())
    {
         file_scan.nextLine();
         lines++;
    }

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