Determine user's input if it is an integer or a double?

Question

I have this code:

    kb.useDelimiter("\\b*[\\s]*");
    int answer = 0;
    String num1, num2;
    char operator;

    System.out.print("Enter calculation: "); // user will input **1+6**

    num1 = kb.nextInt();
    operator = kb.next().charAt(0);
    num1 = kb.nextInt();

    switch(operator)
    {
        case '+':
            if (num1.hasNextInt)
            {
                 int aa= Integer.parseInt(num1);
                 int bb= Integer.parseInt(num2);
                answer = CalculatorMethods.add(aa,bb);
            }
            else
            {
                 //converts the String into Double
            }
            break;
    }

What im trying to do in this code is, the user can input in the program directly like this 1+1 . And what i did is i separate each so it will have 1, + and 1... and if the user inputs an integer number.... then i will convert it to an integer and then calls the method.... else it will convert the String into a double and will then call the method..

So, when i compile the code above, all i get is MANY ERRORS like incompatible types, cannot find symbol hasNextInt.... what is wrong in my code?

ANY HELP WILL BE APPRECIATED.

i change it to what you said.... but it still gives an "cannot find symbol hasNextInt()" error — Raven Maddison
– Raven Maddison, Commented Mar 2, 2015 at 12:34
num1 & num2 are strings. You try to set there an int. (nextInt). And num1&num2 dont have hasNextInt() method. Many strange things there. — pL4Gu33
– pL4Gu33, Commented Mar 2, 2015 at 12:34

nomis · Accepted Answer · 2015-03-02 12:35:05Z

1

Your num1 variable is declared as a String, but you are trying to assign an int to it (i'm assuming kb is an instance of a Scanner). Then you are trying to invoke num1.hasNextInt() which is not a method of a String - i think you meant to say kb.hasNextInt().

answered Mar 2, 2015 at 12:35

nomis

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Comments

AJ. · Accepted Answer · 2015-03-02 12:41:18Z

1

nextInt() returns int so you can not do num1 = kb.nextInt();

neither String or int have hasNextInt

You must declare num1 and num2 as int.

And some changes in switch case:

case '+':

                answer = CalculatorMethods.add(num1,num2);
          break;

edited Mar 2, 2015 at 12:41

answered Mar 2, 2015 at 12:35

AJ.

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2 Comments

Raven Maddison Over a year ago

if i change something like that in the switch case then i wont be able to know if the user inputs an integer or a double

AJ. Over a year ago

First of all look on the Scanner class. You are confusing me. pls take a look at this docs.oracle.com/javase/7/docs/api/java/util/…

atish shimpi · Accepted Answer · 2015-03-02 12:36:30Z

0

Create one API that will tell you your string is integer or double type

public boolean isInteger(String value) { 
    try {
        Integer.parseInt(value);
        return true;
    } catch (NumberFormatException e) {
        return false;
    }
}

Then,

if (isInteger(num1) && isInteger(num2)){ // then check if it is integer do integer operation
   int aa= Integer.parseInt(num1);
   int bb= Integer.parseInt(num2);
   answer = CalculatorMethods.add(aa,bb);
}else{
     //converts the String into Double
}

answered Mar 2, 2015 at 12:36

atish shimpi

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