Programming Drill #19

Due: Monday, November 19
Goal:  More practice with inheritance

Here is an alcoholic beverage class. It has expanded on our previous definition of the Beer class to include wine. There is a 'type' variable set to 0 if it is beer and 1 if it is wine. This is used to calculate the number of drinks, because there are only 5 ounces in a glass of wine but 12 ounces in a glass of beer.

public class AlcoholicBeverage
{
	private String name;
	private double alcohol;
	private int type;		// 0 for Beer, 1 for Wine

	// Constructors
	public AlcoholicBeverage()
	{
		name = "";
		alcohol = 0.0;
	}

	public AlcoholicBeverage(String newName, double newAlcohol, int newType)
	{
		name = newName;
		alcohol = newAlcohol;
		type = newType;
	}

	// Accessors
	public String getName()
	{
		return name;
	}
	public double getAlcohol()
	{
		return alcohol;
	}
	// Mutators
	public void setName(String newName)
	{
		name = newName;
	}
	public void setAlcohol(double newAlcohol)
	{
		alcohol = newAlcohol;
	}

	// This method returns the number of drinks that a person
	// of (weight) pounds can drink using the alcohol percentage in this
	// drink.  Beer is 12 ounces while wine is 5 ounces.
	// It is an estimate.  It assumes the legal limit is 0.08 BAC.
	public double intoxicated(double weight)
	{
		double numDrinks;
		// This is a simplification of the Widmark formula
		if (type == 0)
		{
			// Beer
			numDrinks =  (0.08 + 0.015) * weight / (12 * 7.5 * alcohol);
		}
		else
		{
			// Wine
			numDrinks =  (0.08 + 0.015) * weight / (5 * 7.5 * alcohol);
		}
		return numDrinks;
	}


	/////////////////////////////////////////////////////////////////
	// Main Method
	/////////////////////////////////////////////////////////////////

	public static void main(String[] args)
	{
		AlcoholicBeverage drink1 = new AlcoholicBeverage("Guiness",0.074, 0);  // 0 for beer
		AlcoholicBeverage drink2 = new AlcoholicBeverage("Zinfandel", 0.20, 1); // 1 indicates wine

		double drinks;

		// How many drinks that Bubba can drink
		drinks = drink1.intoxicated(250);
		System.out.printf("Bubba at 250 pounds can drink about " + drinks + " " +
						   drink1.getName() + "'s in one hour until intoxicated.\n");

		drinks = drink2.intoxicated(250);
		System.out.printf("Bubba at 250 pounds can drink about " + drinks + " " +
						   drink2.getName() + "'s in one hour until intoxicated.\n");
	}
}
    

This program will run but it is not very convenient to add a new type of drink - we'd have to add a new code to the 'type' variable. And what if type gets set to an invalid number, like 3? A better organization is to use inheritance.

• Create a Beer class and a Wine class that are child or derived classes from AlcoholicBeverage. These classes should override the intoxicated method with only the calculation pertinent to the type of drink.
• The Beer class and Wine class should have a constructor that takes as input a String that is the name of the drink and a double that is the percent alcohol. There is no need for a 'type' variable anymore, because that information is inherent in the kind of class being created. The constructor should set the name and alcohol class variables (use the super method to invoke the parent's constructor or set the variables directly if you change the variables to type 'protected' in the AlcoholicBeverage class).
• There is no longer a need for the 'type' variable in the AlcoholicBeverage class. Remove all references to it. The intoxicated method in the AlcoholicBeverage class can just return 0 for now.
• Modify the main method to create Beer and Wine instances instead of AlcoholicBeverage. The program should run as before.

Show your completed program to your instructor or email it to kenrick@uaa.alaska.edu by the end of the day.