Lab 5  Comp 170-201 -- Dordal/Nabicht -- Wed, Sept 25, 2002
Final version due Fri Oct 4
The exam is Monday, Sept 30

Animals

Take the Animal class and answer the following questions and 
make the indicated changes:

1. The field _kind is defined as a member field, but never used. 
   Add it to:
        the existing constructor, so it will have form
                Animal(String name, String kind);
        the driver program (eg horse = new Animal("Flash", "horse");)
        toString(), so we get
                (Misty the horse gray legs=4 age=5) 
                
2. Add a *second* constructor, that takes and sets parameters
        name, kind, age, numberLegs, color
   Use it to create a new animal instance.
  
3. Add a new field altogether, with appropriate field accessor
   and mutator. The new field is any animal attribute of your choice: 
   it could be _eyecount, or _hasTail (boolean), or _tailCount 
   (a bit odd, but...), or _hornCount (Triceratops, anyone?).
   Make toString() print out something sensible about your attribute.
   The constructors should all sensibly initialize your attribute (eg to 0),
   but you do *not* have to add it as a parameter.
   
The following are to be done in the Farm class, not in Animal:
   
4. Write a function 
        void setAge(Animal a, int n) 
   **in the Farm class, *NOT* in Animal**, that attempts to set the
   age of the Animal a to n. This can be done as long as a.age() <=n;
   if a.age()>n, print a warning message and leave a unchanged.
   
5. Write a function 
        void moveLeg(Animal donor, Animal recipient)
   that makes donor lose a leg, if it has one, and recipient gains a leg.
   If donor has no legs to start with, nothing at all is done.
   
6. Run your revised class with a few new animals.

Questions:

1. Which member functions (methods) are accessors? Which are mutators?

I guess that's all the questions.


////////////////////////////////////////////////////////
//  class Animal
////////////////////////////////////////////////////////

import java.awt.*;
    
/**
 * Represents an animal
 * peter dordal, 9/25/02 
 */
public class Animal
{
    // instance variables - replace the example below with your own
    private String _kind;
    private String _name;
    private int    _numberLegs;
    private Color  _color;       // list of colors is on p 114 (or below)
    private int    _age;

    /**
     * Constructor for objects of class Animal
     */
    public Animal(String name)
    {
        // initialise instance variables
        _name = name;
        _numberLegs = 0;
        _color = Color.green;   // why this type?
        _age = 0;
    }
    
    // "copy ctor": special kind of ctor for making copies
    public Animal(Animal a) {
        _name = a._name;
        _kind = a._kind;
        _numberLegs = a._numberLegs;
        _color = a._color;
        _age = a._age;
    }


    public void setName (String name) {_name = name;}
    public String name() {return _name;}
    
    public void setColor(Color c) {_color = c;}
    public Color color() {return _color;}
    
    public int legs() {return _numberLegs;}
    public void growLeg() {_numberLegs++;}
    public void loseLeg() {
        if (_numberLegs > 0)
            _numberLegs--;
    }
    
    public void increaseAge() {_age++;}
    public int age() { return _age;}
    
    // why toString??
    public String toString() {
        String result = "(";
        result += _name;
        result += ' ';
        result += color2string(_color);
        result+= " legs=";
        result += _numberLegs;
        result += " age=";
        result += _age;
        result += ")";
        return result;
    } // end of toString

    private String color2string(Color c) {
        if (c == Color.black) return "black";
        else if (c == Color.blue)   return "blue";
        else if (c == Color.cyan)   return "cyan";
        else if (c == Color.gray)   return "gray";
        else if (c == Color.darkGray)return "darkGray";
        else if (c == Color.lightGray)return "lightGray";
        else if (c == Color.green)  return "green";
        else if (c == Color.magenta)return "magenta";
        else if (c == Color.orange) return "orange";
        else if (c == Color.pink)   return "pink";
        else if (c == Color.red)    return "red";
        else if (c == Color.white)  return "white";
        else if (c == Color.yellow) return "yellow";
        else return c.toString();
    } // color2string
} // end of class Animal



////////////////////////////////////////////////////////
//  class Farm
////////////////////////////////////////////////////////

import java.awt.Color;      // this is all we need from java.awt
    
/**
 * Write a description of class Farm here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Farm
{
    public static void main (String[] s)
    {
        Animal cow, duck, horse, cat, chicken, fish;
        duck = new Animal("Rev Graham");
        horse = new Animal("Misty");
        cat = new Animal ("Blackie");
        chicken = new Animal("Red");
        fish = new Animal("Jaws");
        
        duck.growLeg();
        duck.growLeg();
        duck.increaseAge();
        System.out.println(duck.toString());
        
        horse.growLeg();
        horse.growLeg();
        horse.growLeg();
        horse.growLeg();
        horse.setColor(Color.gray);
        for (int i=0; i<10; i++) horse.increaseAge();
        System.out.println(horse.toString());
        
        Animal mandy = new Animal(horse);
        mandy.setName("Mandy");
        System.out.println(horse.toString());
        
        cat.growLeg();
        cat.growLeg();
        cat.growLeg();
        cat.growLeg();
        cat.setColor(Color.black);
        System.out.println(cat.toString());
        
        chicken.growLeg();
        chicken.growLeg();
        chicken.setColor(Color.red);
        chicken.increaseAge();
        System.out.println(chicken.toString());
        
        fish.setColor(Color.yellow);
        //fish.setColor(Color.yellow());          // oops!
        System.out.println(fish.toString());
    }
} // end of Farm