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Thread: HW-how to read a string from a text file

  1. #1
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    Default HW-how to read a string from a text file

    I received this homework assignment, it basically tells me to read GPAs of male and female students from a text file and then output averages to another text file.

    This is an idea of what the file looks like that is read:
    f 3.40
    f 4.00
    m 3.56
    m 3.80
    f 2.30
    f 3.95

    My question is how do I read whether the character before the gpa is "m" or "f"?

    This is what I have so far:

    import java.io.*;
    import java.util.*;
     
    public class HW2 {
     
      public static void main (String[] args) throws FileNotFoundException {
     
        double mGPA, fGPA;
        String m,f;
        double mGPAsum = 0;
        double fGPAsum = 0;
        int numberMales = 0;
        int numberFemales = 0;
     
     
        Scanner inFile=new Scanner(new FileReader("input.txt"));
        PrintWriter outFile = new PrintWriter("outputGPA.txt");
     
        while (inFile.hasNext()) {
     
          if (inFile.equals("f")) {
            double gpa = inFile.nextDouble();
            fGPAsum += gpa;
            numberFemales++;
          }
     
          if (inFile.equals("m")) {
            double gpa = inFile.nextDouble();
            mGPAsum += gpa;
            numberMales++;
          }
        }
     
        outFile.println("Sum female GPA = " + fGPAsum);
        outFile.println("Sum male GPA = " + mGPAsum);
        outFile.println("Female count = " + numberFemales);
        outFile.println("Male count = " + numberMales);
     
        fGPA = fGPAsum / numberFemales;
        mGPA = mGPAsum / numberMales;
     
        outFile.println("Average female GPA = " + fGPA);
        outFile.println("Average male GPA = " + mGPA);
     
        inFile.close();
        outFile.close();
      }
    }

    And this is what it's saying:

    2 warnings found:

    Warning: The local variable m is never read

    Warning: The local variable f is never read


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: HW-how to read a string from a text file

    I'm pretty confused by your approach here. The inFile variable is a Scanner, right? So why are you comparing it to a String? That's not how you test the Scanner's input. I suggest reading the API as well as the tutorial to figure out how to correctly use Scanner. By the way, those links were the first 2 hits for googling "java scanner", which is a process you should try to get more accustomed to.
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  3. #3
    Super Moderator Norm's Avatar
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    Default Re: HW-how to read a string from a text file

    Also posted a HW-how to read a string from a text file - Dev Shed
    If you don't understand my answer, don't ignore it, ask a question.

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