Fahrenheit to Celsius conversion yields only 0.0 and -0.0

Question

I\'m on the 8th chapter (Methods, Constructors, and Fields) of my Java methods book and I\'m having a problem with one of my exercises.

The provided code is Tempera

Answer 1

The problem seems to be 5/9. They are seen as an integer, and 5/9 is 0.something which is 0 as an integer. So whatever * 0 = +-0 :)

Place a "d" after the numbers, (5d/9d) forcing the compiler to consider them doubles.

Answer 2

change (5 / 9) to (5.0 / 9.0) to let java know, that you want real numbers division.

Answer 3

If you don't return anything set the return type to void. If you like to return doubles, you have to use doubles in calculations. 5/9 is always zero because 5 and 9 are integers. 5.0/9.0 is a different calculation on doubles.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.DecimalFormat;

public class FCConverter
{
  private double Celsius;
  private double Fahrenheit;
  public void setFahrenheit (double degrees)
  {
     Celsius = (degrees - 32.0) * (5.0 / 9.0);
  }
  public double getCelsius ()
  {
      return Celsius;
  }
  public void setCelsius (double degrees)
  {
      Fahrenheit = (degrees * 9.0 / 5.0 + 32.0);
  }
  public double getFahrenheit ()
  {
      return Fahrenheit;
  }
}

Answer 4

In integer math (5 / 9) = 0.

and (degrees - 32) * (5 / 9); will always be 0 you need to use doubles or something.

Answer 5

import java.util.Scanner;
public class HelloWorld {

    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);  // Reading from System.in

        System.out.println("Enter  the number of Fahrenheit temperatures to convert to Kelvins");
// opts for the user to enter a number 

        int F = reader.nextInt() ; // Scans the next token of the input
        double f = 5/9d;
        System.out.println(f);
        double x = F -32;
        System.out.println(x);
        double K = (f*x)+ 273.0; // the formulae to calculate temperature  in Kelvin
        System.out.println( +F + " Fahrenheit is equal " +K + " Kelvins" ) ;
        reader.close();




    }       

}