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Thread: Input output file help

  1. #1
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    Default Input output file help

    Hey all, this is my first post and its nice to meet you all.

    I appreciate all your help.

    I have most of my program done already, but I'm having some problems with input and output files. There are 2 files of each. Lab4Input1.txt and 2 and Lab4Output1.txt and 2. The problem I'm having is selecting which file a user picks.

    The code is as follows for what I'm having issues with:

    Scanner keyIn = new Scanner(System.in); //assigns "keyIn" to keyboard
    //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    int fileNum;
    String inName;
    String outName;
    boolean inputBad = true;

    do
    {
    System.out.print("Please enter file number, 1 or 2 > ");
    fileNum = keyIn.nextInt( );

    if (fileNum == 1 || fileNum == 2);
    boolean inputBad = false;


    }
    while (inputBad = true);



    ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

    if (fileNum == 1)
    {
    Scanner inName = new Scanner(new FileReader("Lab4Input1.txt"))
    PrintWriter outName = new PrintWriter("Lab4Output1.txt");
    }
    else
    {
    inName = "Lab4Input2.txt";
    outName = "Lab4Output2.txt";
    }

    The first part I don't understand, its what my teacher said, but I dont know what it means. Why do I need to the inputBad = false; stuff.

    The second part is what I am really stuck on. A user is supposed to type in which file he wants to choose, 1 or 2. My problem is making the code for how it chooses which files to use.


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Input output file help

    The first part is just making sure the user enters a 1 or 2. If the user enters something else, it will repeat the question.

    As for the second part, read this: Lesson: Basic I/O (The Java™ Tutorials > Essential Classes)
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    Member OutputStream's Avatar
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    Default Re: Input output file help

    while (inputBad = true);

    Shouldn't that be:

    while (inputBad == true);

    Or even shorter:

    while (inputBad);

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    Default Re: Input output file help

    Also, one other thing is that your if statement contains a null statement because you follow it immediately with a semicolon. If you want the next line of code to execute when the if condition is fulfullied, remove the semicolon.

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    Default Re: Input output file help

    Quote Originally Posted by mjpam View Post
    Also, one other thing is that your if statement contains a null statement because you follow it immediately with a semicolon. If you want the next line of code to execute when the if condition is fulfullied, remove the semicolon.
    Good catch. Better yet, always use {} blocks for if statements and loops.
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