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Thread: reading a string from input

  1. #1
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    Default reading a string from input

    Hi so I am wondering how it would be possible to read a string from input. for instance:
    public class TestInput1{
     
        public static void main (String[]args){
        double firstNo = readDouble("First number?");
        int operator = readInt("Operator - type 1 for *, 2 for +, 3 for -, or 4 for /");
        Double secondNo = readDouble("Second number?");
        if (operator == 1) {
            System.out.println(firstNo + " times " + secondNo + " = " + (firstNo*secondNo));
        }
        else if (operator == 2){
            System.out.println(firstNo + " plus " + secondNo + " = " + (firstNo+secondNo));
        }
        else if (operator == 3){
            System.out.println(firstNo + " minus " + secondNo + " = " + (firstNo-secondNo));
        }
        else if (operator == 4){
            System.out.println(firstNo + " divided by " + secondNo + " = " + (firstNo/secondNo));
        }
        }
     
        public static int readInt(String prompt){
    System.out.println(prompt);
    java.util.Scanner keyboard = new java.util.Scanner(System.in);
    return keyboard.nextInt();
    }
    public static String readString(String prompt){
    System.out.println(prompt);
    java.util.Scanner keyboard = new java.util.Scanner(System.in);
    return keyboard.nextLine();
    }
    public static double readDouble(String prompt){
    System.out.println(prompt);
    java.util.Scanner keyboard = new java.util.Scanner(System.in);
    return keyboard.nextDouble();
    }
    }

    When I first wrote this, I had it so that the user typed in the actual operator e.g. * or + however when I went to check the variable like this:

    public class TestInput1{
     
        public static void main (String[]args){
        double firstNo = readDouble("First number?");
        String operator = readString("Operator --> *, +, -, or /");
        Double secondNo = readDouble("Second number?");
        if (operator == *) {
            System.out.println(firstNo + " times " + secondNo + " = " + (firstNo*secondNo));
        }
        else if (operator == +){
            System.out.println(firstNo + " plus " + secondNo + " = " + (firstNo+secondNo));
        }
        else if (operator == -){
            System.out.println(firstNo + " minus " + secondNo + " = " + (firstNo-secondNo));
        }
        else if (operator == /){
            System.out.println(firstNo + " divided by " + secondNo + " = " + (firstNo/secondNo));
        }
        }
     
        public static int readInt(String prompt){
    System.out.println(prompt);
    java.util.Scanner keyboard = new java.util.Scanner(System.in);
    return keyboard.nextInt();
    }
    public static String readString(String prompt){
    System.out.println(prompt);
    java.util.Scanner keyboard = new java.util.Scanner(System.in);
    return keyboard.nextLine();
    }
    public static double readDouble(String prompt){
    System.out.println(prompt);
    java.util.Scanner keyboard = new java.util.Scanner(System.in);
    return keyboard.nextDouble();
    }
    }

    it didn't like it, and wouldn't check the variable, an error just appeared. I didn't post this in "what's wrong with my code?" because I solved the problem, but I would like to know how to solve this in future without the crude int variable instead.
    thanks,
    Skeptile


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: reading a string from input

    it didn't like it,
    Please explain and post the full text of any error messages
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
    Member
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    Default Re: reading a string from input

    It would help if you compared strings using .equals() instead of ==

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