Temperature Conversion

Question

Hi to all!
It's my first post here.
I just started my very first java class, and I have problem with my assignment.
I have to write a program that accepts an integer # followed by a space and one letter, C or F. It should then convert number to opposite degrees (C or F).
Example of output:
Enter temperature: 35 F
Temperature in C is: 1.6
I managed to write the code, but I have a feeling that there is easier way to do this (while loop?).
Also, I'm getting following error when I input letter other than C or F, shouldn't it go straight to "else" in this case?
Enter temperature: 35 D
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String ind
ex out of range: 4
at java.lang.String.charAt(Unknown Source)
at TempConversion.main(TempConversion.java:57)
import java.util.Scanner;          // Needed for the scanner class
public class TempConversion
     public static void main(String[] args)
          String temperature;          // To hold user's input
          Scanner keyboard = new Scanner(System.in);
          System.out.print("Enter temperature: ");
          temperature = keyboard.nextLine();
          if (temperature.charAt(1) == ' ' && temperature.charAt(2) == 'F')
               String temp1 = temperature.substring(0,1);
               double temp1d = Double.parseDouble(temp1);
               System.out.println("Temp1 F to C: "+(5.0/9.0)*(temp1d-32.0));
          else if (temperature.charAt(1) == ' ' && temperature.charAt(2) == 'C')
               String temp1 = temperature.substring(0,1);
               double temp1d = Double.parseDouble(temp1);
               System.out.println("Temp1 C to F: "+(((9.0/5.0)*temp1d)+32.0));
          else if (temperature.charAt(2) == ' ' && temperature.charAt(3) == 'F')
               String temp2 = temperature.substring(0,2);
               double temp2d = Double.parseDouble(temp2);
               System.out.println("Temp2 F to C: "+(5.0/9.0)*(temp2d-32.0));
          else if (temperature.charAt(2) == ' ' && temperature.charAt(3) == 'C')
               String temp2 = temperature.substring(0,2);
               double temp2d = Double.parseDouble(temp2);
               System.out.println("Temp1 C to F: "+(((9.0/5.0)*temp2d)+32.0));
          else if (temperature.charAt(3) == ' ' && temperature.charAt(4) == 'F')
               String temp3 = temperature.substring(0,3);
               double temp3d = Double.parseDouble(temp3);
               System.out.println("Temp3 F to C: "+(5.0/9.0)*(temp3d-32.0));
          else if (temperature.charAt(3) == ' ' && temperature.charAt(4) == 'C')
               String temp3 = temperature.substring(0,3);
               double temp3d = Double.parseDouble(temp3);
               System.out.println("Temp1 C to F: "+(((9.0/5.0)*temp3d)+32.0));
          else if (temperature.charAt(4) == ' ' && temperature.charAt(5) == 'F')
               String temp4 = temperature.substring(0,4);
               double temp4d = Double.parseDouble(temp4);
               System.out.println("Temp4 F to C: "+(5.0/9.0)*(temp4d-32.0));
          else if (temperature.charAt(4) == ' ' && temperature.charAt(5) == 'C')
               String temp4 = temperature.substring(0,4);
               double temp4d = Double.parseDouble(temp4);
               System.out.println("Temp1 C to F: "+(((9.0/5.0)*temp4d)+32.0));
          else
               System.out.println("Input format is invalid.");
}

Answer 1

stdunbar wrote:
Can I suggest two things: (1) use the trim() method (http://java.sun.com/javase/6/docs/api/java/lang/String.html#trim%28%29) to not care how many spaces are before or after the String you got from nextLine() and (2) use split (http://java.sun.com/javase/6/docs/api/java/lang/String.html#split%28java.lang.String%29) to then pull apart the String into the individual pieces. You can then examine the resulting String[] for what you expect to find.
Edited by: stdunbar on Nov 23, 2009 12:26 PM - these are the worst forums in the world to provide useful links with[trim method link|http://java.sun.com/javase/6/docs/api/java/lang/String.html#trim%28%29]
[split method link|http://java.sun.com/javase/6/docs/api/java/lang/String.html#split%28java.lang.String%29]
Or in bare form...
[http://java.sun.com/javase/6/docs/api/java/lang/String.html#trim%28%29]
[http://java.sun.com/javase/6/docs/api/java/lang/String.html#split%28java.lang.String%29]
Although I still think Scanner.nextInt() followed by next() or nextLine() is simpler.