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Thread: File input and file output

  1. #1
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    Default File input and file output

    Could someone help me figure out why my program won't input the data back onto the screen after it output it onto a text file
    Thanks


    import java.io.IOException;
    import java.io.PrintWriter;
    import java.io.File;
    import java.util.Scanner;
    import java.util.Random;
     
    public class BottleCapPrize
    {
        public static void main(String[]args) throws IOException
        {
            PrintWriter outFile = new PrintWriter(new File("MonteCarlo.txt"));
            Scanner inFile = new Scanner(new File("MonteCarlo.txt"));
            Random randNum = new Random();
            int bottleCapNum = 0;
            int wins = 0;
            int bottleCapInput = 0;
            int token;
     
            Scanner userInput = new Scanner (System.in);
     
            //
            System.out.print("Please enter the number of trials: ");
            int uInput = userInput.nextInt();
     
           for (int counter = 1; counter <= uInput; counter++) {  
              int randNum1 = 0;  
              while (randNum1 != 1) {  
                        randNum1 = randNum.nextInt(5);  
                        System.out.println("randNum1 = " + randNum1);  
                        bottleCapNum++;  
                    }  
              wins++;  
              bottleCapNum++;  
              System.out.println("Counter = " + counter + " bottleCapNum = "  
                            + bottleCapNum + " wins = " + wins);
              outFile.println(bottleCapNum);
     
                }  
           outFile.close( );
            while(inFile.hasNextInt()); 
              { token = inFile.nextInt();
             System.out.println(token);}
               inFile.close();
     
            }
            }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: File input and file output

    What does the code print out when it executes?

    Does the program end normally?

    Add some println statements so you can see where the code is executing and find the last statement that it executed.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: File input and file output

    I'm trying to make the program output the number into the file and then get it back from that file.

  4. #4
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    Default Re: File input and file output

    What does the code print out when it executes?

    Does the program end normally?

    Add some println statements so you can see where the code is executing and find the last statement that it executed.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: File input and file output

    It would output the result to the text file but it seem the program is not ending. It get stuck I'm guessing at the line to read the text file and print them on the screen.

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    Default Re: File input and file output

    Try adding some println statements to see where the code is hanging/stuck. Sometime you need them every other statement so you can tell which statement the program is hanging on. If one println doesn't print, then you know that the program is hung on the statement just in front of it.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: File input and file output

    The code is stoping after it print "outFile.println(bottleCapNum);" So the while loop to read the file is where the program stuck at.

  8. #8
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    Default Re: File input and file output

    What statement is the one before the last println statement that did not print?

    EDIT: corrected above

    When it did not print, that means the statement before it is hung.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: File input and file output

    while(inFile.hasNextInt());
    { token = inFile.nextInt();

  10. #10
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    Default Re: File input and file output

    That's two statements. Which one is it hanging on? Put a println between them.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: File input and file output

    This is what I put

    while(inFile.hasNextInt());
    {System.out.println(inFile);
    token = inFile.nextInt();
    System.out.println(token);}

    But it did not print the inFile so it hanging at the start of the while loop.

  12. #12
    Super Moderator Norm's Avatar
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    Default Re: File input and file output

    But it did not print the inFile so it hanging at the start of the while loop.
    Take a close look at the while statement and make sure there isn't a statement ending ; before the { that surrounds the code that is supposed to be in the loop.

    The while and do-while Statements (The Javaô Tutorials > Learning the Java Language > Language Basics)
    If you don't understand my answer, don't ignore it, ask a question.

  13. The Following 2 Users Say Thank You to Norm For This Useful Post:

    jtmnf (December 27th, 2012), maple1100 (December 26th, 2012)

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    Default Re: File input and file output

    Oh wow... I miss such a little detail. Thank you so much. Can't believe I been trying to figure out what wrong and it end up being that ; T~T

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