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Thread: Very Simple Beginning Java Help Needed

  1. #1
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    Default Very Simple Beginning Java Help Needed

    I am currently teaching myself Java to prepare for college. I would like to have some prior experience with the language before entering the class headfirst and becoming completely lost.

    I'm making a program to perform very simplistic calculations. The problem I'm having is that my program should ask for input from the user three times. Twice for numbers and once for the operator. After the two numbers are entered, though, my program outputs "answer is 0.0" (the default value of double answer.)

    import java.util.Scanner;
    public class Calculator
    {
    	public static void main(String[] args)
    	{
    		Scanner input = new Scanner(System.in);
     
    		System.out.print("Enter first number: ");
    		double number1 = input.nextDouble();
     
    		System.out.print("Enter second number: ");
    		double number2 = input.nextDouble();
     
    		System.out.print("Enter operator: ");
    		String operator = input.nextLine();
    		double answer = 0;
     
    		if(operator == "+")
    		{
    			answer = number1 + number2;
    		}
    		else if(operator == "-")
    		{
    			answer = number1 - number2;
    		}
    		else if(operator == "*")
    		{
    			answer = number1 * number2;
    		}
    		else if(operator == "/")
    		{
    			answer = number1 / number2;
    		}
     
    		System.out.println("answer is " + answer);
    	}
     
    }


  2. #2
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    Default Re: Very Simple Beginning Java Help Needed

    Read the following to understand the differences between == operator and the .equals() method:
    http://www.javaprogrammingforums.com...-mistakes.html

    For the operator variable, to stop it skipping, you may either change it to input.next() or
    call input.nextLine() by itself before you prompt for operator.
    Calling input.nextLine() by itself essentially clears previous inputs for you.
    Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code

  3. The Following User Says Thank You to newbie For This Useful Post:

    lgore93 (August 11th, 2011)

  4. #3
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    Default Re: Very Simple Beginning Java Help Needed

    Thanks! Your link was very informative, too. I just started a tutorial on Java today and still feel very much a noob. ha.

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