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Thread: Java int comparison

  1. #1
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    Default Java int comparison

    I'm trying to see if the user input is an int but the error I'm getting is int cannot be a deference could someone explain to me what does that mean? Thanks

    import java.util.Scanner;
     
    public class FibonacciNumbersTester
    {
        public static void main(String[]args)
        {   //Variables
            Scanner userNum = new Scanner(System.in);
            Scanner userDed = new Scanner(System.in);
            String userChoice = "Y";
            FibonacciNumbers reMethod  = new FibonacciNumbers();
            while(userChoice.equalsIgnoreCase("Y"))
            {
            System.out.print("What integer would you like to calculate the Fibonacci number for? ");
            int NumTo  = userNum.nextInt();
            if(NumTo.hasNextInt())
            {
                System.out.println("Please enter an integer!");
            }
            int fiboPrint = reMethod.numFibo(NumTo);
            reMethod.printData(fiboPrint);
     
            System.out.print("Would you like to continue? (Y/N)");
            userChoice = userDed.next();
            }
            }
        }


  2. #2
    Super Moderator curmudgeon's Avatar
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    Default Re: Java int comparison

    You're trying to call a method off of an int variable which doesn't make sense to the compiler (or to me). Get rid of the offending statement and try something different.

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    Default Re: Java int comparison

    I just realize I use the int variable instead of the scanner in the if statement. Thanks you.

    --- Update ---

    I'm sorry, I marked the thread by accident. Here is what I have so far. Right now, the program test if the user input is a positive integers if it not a positive or an integer, it would print "Please input an integers" but if it an integer, it would give that integer to the object parameters. The program is stuck at "" int NumTo = userNum.nextInt();" Thanks
    ** I understand " int NumTo = userNum.nextInt();" is awaiting for user input but how can I make it use the input that is input earlier at "Please enter the fibonacci number......".
    import java.util.Scanner;
     
    public class FibonacciNumbersTester
    {
        public static void main(String[]args)
        {   //Variables
            Scanner userDed = new Scanner(System.in);
            Scanner userTest = new Scanner(System.in);
            String userChoice = "Y";
            FibonacciNumbers reMethod  = new FibonacciNumbers();
            while(userChoice.equalsIgnoreCase("Y"))
            {
            Scanner userNum = new Scanner(System.in);
            System.out.print("What integer would you like to calculate the Fibonacci number for? ");
     
            if(!userNum.hasNextInt() )
            {
                System.out.println("Please enter an integer!");
            }
            else if(userNum.nextInt() < 0 )
            {   
                System.out.println("Please enter a postive integer!");
     
            }
            else
            {
                System.out.println("If this print, this is where the program stuck");
                int NumTo = userNum.nextInt();
                int fiboPrint = reMethod.numFibo(NumTo);
                reMethod.printData(fiboPrint);
            }
            System.out.print("Would you like to continue? (Y/N)");
            userChoice = userDed.next();
     
            }
            }
        }

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Java int comparison

    "Please enter the fibonacci number
    Where is that message? I don't see it in the posted code.

      else if(userNum.nextInt() < 0 )
    What is done with the number read by nextInt() in the above statement?
    It needs to be assigned to a variable if you want to save and use it.
    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
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    Default Re: Java int comparison

    " "Please enter the fibonacci number "- I mean at "What integer would you like to calculate the Fibonacci number for? " - Sorry.

    else if(userNum.nextInt() < 0 ) - This is use to compare if the number inputted by the user is a negative number.

    This is a test run of the program.

    What integer would you like to calculate the Fibonacci number for? 2.8
    Please enter an integer!
    Would you like to continue? (Y/N)Y
    What integer would you like to calculate the Fibonacci number for? 2
    If this print, this is where the program stuck
    **Then it await for the user input again right here even though I enter it "2". Thanks

  6. #6
    Super Moderator Norm's Avatar
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    Default Re: Java int comparison

    This is use to compare if the number inputted by the user
    What happens to the number that is inputted by the user in that statement? Where does it go?

    You should first read it into a variable, THEN test it in case you want to use it.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Java int comparison

    What data type should I read the user input into? If I use Int, it would give me an error when user input a double.

  8. #8
    Super Moderator Norm's Avatar
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    Default Re: Java int comparison

    The hasNext methods do not read any data. They test if data is available to be read.
    The next methods do read data that should be assigned to a variable so it can be used later.
    This statement does NOT save what was read:
      else if(userNum.nextInt() < 0 )
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Java int comparison

    Thanks you for clearing that up! Could you give me a hint of which part of the program should I assign what it read so it can be use in the else statement? Thanks

  10. #10
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    Default Re: Java int comparison

    Before writing any code, decide what the code is supposed to do.
    When to test if there is some input
    when to print out an error message
    when to read the input
    when to use the input
    If you don't understand my answer, don't ignore it, ask a question.

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