/** 
* An instance of this class represents a temperature that can be expressed
* in either the Fahrenheit or Celsius scale.
* 
* @author P.M.J. (modified slightly by R.W.M)
* @version 2009-08-19
*/
public class Temperature {

  // Instance Variable(s) 
  // ====================

  private double fahrenheitReading;


  // Constructor Method(s)
  //======================

  /**
  * Initializes the temperature to wather's freezing point.
  */
  public Temperature() {
    fahrenheitReading = 32.0;
  }

  /**
  * Initializes the temperature to the given Fahrenheit reading.
  */
  public Temperature(double f) {
    fahrenheitReading = f;
  }


  // Observer Method(s)
  //===================

  /**
  * Returns the temperature as a Fahrenheit reading.
  */
  public double getAsFahrenheit() {
    return fahrenheitReading;
  }
  
  /**
  * Returns the temperature as a Celsius reading.
  */
  public double getAsCelsius() {
    return fahrenheitToCelsius(fahrenheitReading);
  }


  // Mutator Method(s)
  //==================

  /**
  * Sets the temperature to the given Fahrenheit reading.
  */
  public void setAsFahrenheit(double f) {
    fahrenheitReading = f;
  }
  
  /**
  * Sets the temperature to the given Celsius reading.
  */
  public void setAsCelsius(double c) {
    fahrenheitReading = celsiusToFahrenheit(c);
  }
 

  // Conventional Method(s)
  //=======================

  /**
  * Returns the current Fahrenheit reading as a printable string value.
  */
  public String toString() {
     return getAsFahrenheit() + " F";
  }


  // Private Method(s)
  //==================

  /**
  * Given a Fahrenheit reading, returns the corresponding Celsius reading.
  */
  private double fahrenheitToCelsius(double f) {
    return (5.0 * (f - 32.0)) / 9.0;  
  }
    
  /**
  * Given a Celsius reading, returns the corresponding Fahrenheit reading.
  */
  private double celsiusToFahrenheit(double c) {
      return ((9.0 * c) / 5.0) + 32.0;
  }

}