1. ./Car.java
2. ./CarLot.java
3. ./Chicken.java
4. ./Electric.java
5. ./Hybrid.java
6. ./Movable.java
7. ./OverloadPlay.java
8. ./Powered.java

/**
 * Demonstrates use of interface.
 * Since Car implements Powered, which extends Movable, Car must implement
 * the move method and milesPer
 */
public class Car implements Powered {
    
    private double mpg;
    private double xcoord;
    private double ycoord;
    
    protected int tankSize = 15; // in gallons
    
    public Car(double mpg) {
        this.mpg = mpg;
        xcoord = 0;
        ycoord = 0;
    }
    
    @Override
    public String toString() {
        return xcoord + ", " + ycoord;   
    }
    
    public double milesPerGallon() {
        return mpg;
    }
    
    public void move(double x, double y) {
        xcoord += x;
        ycoord += y;
    }
    
    public int getTankSize() {
        System.out.println("Car's getTankSize()");
        return tankSize;   
    }
    
    public static String staticMethod() {
        return "Car's static method";
    }
    
    public static void main(String args[]) {
        Car car = new Car(32);
        car.move(1, 1);
        System.out.println(car);
        
        System.out.println(SPEED_LIMIT);
        System.out.println(car.getTankSize());
        System.out.println(staticMethod());
    }
}

/**
 * Demonstrates that static methods are inherited but cannot be overridden.
 */
public class CarLot {

    public static void main(String[] args) {
        
        Car[] mycars = new Car[3];
        
        Car car = new Car(35);
        Hybrid hybrid = new Hybrid();
        Electric electric = new Electric();
        
        mycars[0] = car;
        mycars[1] = hybrid;
        mycars[2] = electric;
        
        // note that mycar[1] and h are two variables referencing
        // the *same* object--of type Hybrid.  
        
        // This code calls an instance method, so dynamic dispatch is used.
        // Both execute the Hybrid class's method
        System.out.println(hybrid.getTankSize());
        System.out.println(mycars[1].getTankSize());
            
        // This code calls a static method.
        // The first will call Hybrid's static method, which makes sense
        // The second will call Car's static method, because mycars[1] is a
        // Car variable.  Dynamic dispatch is not used.
        System.out.println(hybrid.staticMethod());
        System.out.println(mycars[1].staticMethod());
        
        // Output:
        // Hybrid's static method
        // Car's static method
    }

}

import java.util.Arrays;

/**
 * A simple Java class that models a Chicken. The state of the chicken is its
 * name, height, weight, and gender.
 *
 * Made several of the accessor methods final because child classes shouldn't need to change them.
 * 
 * Implements the Comparable interface, comparing chickens by their height.
 *
 * @author CSCI209
 */
public class Chicken implements Comparable {

    // ------------ INSTANCE VARIABLES -------------------

    /** the chicken's name */
    private String name;

    /** the height of the chicken in centimeters */
    private int height;

    /** the weight of the chicken in pounds */
    private double weight;

    /** true iff the chicken is a female */
    private boolean isFemale;


    /** default name for chickens */
    public static String DEFAULT_NAME = "BUBBA";

    /** the name of the farm the chickens are on */
    public static String FARM = "McDonald";

    /** the amount of weight the chicken gains during feeding */
    private static double WEIGHT_GAIN = .3;

    /** the amount of height the chicken gains during feeding */
    private static int HEIGHT_GAIN = 1;

    /** the amount of weight difference we are okay with */
    public static double ERROR_TOLERANCE = .0001;

    /**
     * Constructs a chicken with the given characteristics.
     * 
     * @param name the name of the chicken
     * @param height the height of the chicken in centimeters
     * @param weight the weight of the chicken in pounds
     * @param isFemale whether the chicken is female
     */
    public Chicken(String name, int height, double weight, boolean isFemale ) {
        this.name = name;
        this.height = height;
        this.weight = weight;
        this.isFemale = isFemale;
    }

    /**
     * Constructs a chicken with the given characteristics and assumes
     * the chicken is female.
     * 
     * @param name the name of the chicken
     * @param height the height of the chicken in centimeters
     * @param weight the weight of the chicken in pounds
     */
    public Chicken(String name, int height, double weight) {
        this( name, height, weight, true );
    }

    /**
     * Constructs a chicken with the given characteristics, assumes
     * the chicken's name is Bubba (defined by DEFAULT_NAME) and that
     * it is female.
     * @param height the height of the chicken in centimeters
     * @param weight the weight of the chicken in pounds
     */
    public Chicken( int height, double weight ) {
        this( DEFAULT_NAME, height, weight, true);
    }

    /**
     * Returns a string representation of the chicken.
     * Format:
     * <br/>Chicken name: &lt;name&gt;
     * <br/>weight: &lt;weight&gt; pounds
     * <br/>height: &lt;height&gt; cm
     * <br/>female/male
     * <p>Weight is displayed to one decimal place
     * @return a string representation of this Chicken
     */
    @Override
    public String toString() {
        StringBuffer rep = new StringBuffer("Chicken name: ");
        rep.append(name);
        rep.append("\nweight: ");
        rep.append(String.format("%.1f", weight));
        rep.append(" pounds\nheight: ");
        rep.append(height);
        rep.append(" cm\n");
        rep.append( isFemale? "female" : "male"); // Java ternary operator; also available in C
        return rep.toString();
    }

    /**
     * Determines if two Chickens are equivalent, based on their
     * name, height, weight, and sex.
     */
    @Override
    public boolean equals(Object o) {

        if( o == this ) {
            return true;
        }

        Chicken other = (Chicken) o;

        if( ! other.getName().equals(this.getName() ) ) {
            return false;
        }

        if( other.getHeight() != this.getHeight() ) {
            return false;
        }

        double difference = this.getWeight() - this.getWeight();
        if( difference > ERROR_TOLERANCE ) {
            return false;
        }

        if( this.isFemale() ) {
            return other.isFemale();
        } else {
            return ! other.isFemale();
        }

    }

    /**
     * Returns a positive integer if the otherObject is not a chicken.
     * Otherwise, returns a negative integer if this chicken is smaller
     * in height than than the object passed as a parameter, 
     * returns a positive integer if this chicken is greater in height
     * than the object passed as a parameter, and returns a 0 if the 
     * two chickens have the same height.
     */
    public int compareTo(Object otherObject) {
        if( ! (otherObject instanceof Chicken) ) {
            return 1;
        }
        Chicken other = (Chicken) otherObject;
        if (height < other.getHeight() )
            return -1;
        if (height > other.getHeight())
            return 1;
        return 0;
        // simpler implementation : return height-other.getHeight()
    }


    //
    // ----------- GETTER METHODS ------------
    // (also Accessor methods)

    /**
     * Returns the height of the chicken in centimeters
     *
     * @return the height of the chicken, in centimeters
     */
    public final int getHeight() {
        return height;
    }

    /**
     * Returns the weight of the chicken in pounds
     * @return the weight of the chicken, in pounds
     */
    public final double getWeight() {
        return weight;
    }

    /**
     * Returns the chicken's name
     * @return the name of the chicken
     */
    public final String getName() {
        return name;
    }

    /**
     * Returns whether this chicken is female.
     * 
     * @return true if the chicken is female and false otherwise.
     */
    public boolean isFemale() {
        return isFemale;
    }


    //
    // ------------- MUTATORS -----------
    //

    /**
     * Feeds the chicken--making the chicken grow
     */
    public void feed() {
        weight += WEIGHT_GAIN;
        height += HEIGHT_GAIN;
    }

    //
    // ------------- SETTERS ----------
    //

    /**
     * Sets the name of the chicken
     * 
     * @param n
     *            the name of the chicken
     */
    public void setName(String n) {
        name = n;
    }

    /**
     * Sets the height of the chicken
     * 
     * @param h
     *            the height of the chicken, in cm
     */
    public void setHeight(int h) {
        height = h;
    }

    /**
     * Sets the weight of the chicken
     * 
     * @param w
     *            the weight of the chicken, in pounds
     */
    public void setWeight(double w) {
        weight = w;
    }

    /**
     * @param args
     *            the command-line arguments
     */
    public static void main(String args[]) {

        int fredHeight = 38;
        Chicken chicken = new Chicken("Fred", fredHeight, 2.0, false);

        System.out.println(chicken);

        if( chicken.getHeight() != fredHeight ) {
            System.err.println("Problem likely in constructor setting height");
        }
        if( !chicken.getName().equals("Fred") ) {
            System.err.println("Problem likely in constructor setting name");
        }

        chicken.feed();

        int newFredHeight = chicken.getHeight();
        System.out.println(chicken.getName() + " is now " + newFredHeight +
                           " cm tall.");

        chicken.feed();

        System.out.println("He's a growing boy at " + chicken.getHeight() + " cm tall and " + chicken.getWeight() + " pounds");

        String expectedRep = "Chicken name: Fred\nweight: 2.6 pounds\nheight: 40 cm\nmale";
        String actualRep = chicken.toString();

        // Demonstrates trickiness with testing with doubles
        if( ! actualRep.equals(expectedRep) ) {
            System.err.println("Problem in toString");
            System.err.println("\tActual: " + actualRep);
            System.err.println("\tExpected: " + expectedRep);
        }

        Chicken trivialMatch = chicken;

        if( ! chicken.equals(trivialMatch) ) {
            System.err.println("Problem in equals");
            System.err.println("\tActual: " + chicken.equals(trivialMatch) );
            System.err.println("\tExpected: " + true);
        }

        Chicken grownFred = new Chicken("Fred", 40, 2.6, false);
        // This doesn't work -- again issue with comparing doubles
        if( ! chicken.equals(grownFred) ) {
            System.err.println("Problem in equals");
            System.err.println("\tActual: " + chicken.equals(grownFred) );
            System.err.println("\tExpected: " + true);
        }


        // ---- creating tests for chickens -----

        String[] names = {"Rocky", "Baby Chicken"};
        double[] weights = {4.0, .8};
        int[] heights = {50, 4};
        
        Chicken[] chickens = new Chicken[3];

        for( int i=0; i < names.length; i++ ) {
            Chicken thisChicken = new Chicken( names[i], heights[i], weights[i] );
            chickens[i] = thisChicken;

            if( !thisChicken.getName().equals(names[i]) ) {
                System.err.println("Problem likely in constructor setting name");
                System.err.println("\tActual: " + thisChicken.getName());
                System.err.println("\tExpected: " + names[i]);
            }


            if( thisChicken.getWeight() != weights[i] ) {
                System.err.println("\tError in getWeight for Chicken " + i );
                System.err.println("\tActual: " + thisChicken.getWeight());
                System.err.println("\tExpected: " + weights[i] );
            }

            // feed the chicken and check the state
            thisChicken.feed();
            if( thisChicken.getWeight() != weights[i] + WEIGHT_GAIN ) {
                System.err.println("Error in feed weight for Chicken " + i);
                System.err.println("\tActual: " + thisChicken.getWeight());
                System.err.println("\tExpected: " + (weights[i] + WEIGHT_GAIN) );
            }

            if( thisChicken.getHeight() != heights[i] + HEIGHT_GAIN ) {
                System.err.println("Error in feed height for Chicken " + i);
                System.err.println("\tActual: " + thisChicken.getHeight());
                System.err.println("\tExpected: " + (heights[i] + HEIGHT_GAIN) );
            }

            // feed the chicken again and check the state

            thisChicken.feed();

            // NOTE: this test may fail, but tried to address by giving some
            // error tolerance on the weight
            double expectedWeight2 = weights[i] + 2 * WEIGHT_GAIN;
            int comparison = Double.compare(thisChicken.getWeight(),  expectedWeight2 );
            if( comparison != 0 ) {
                if( thisChicken.getWeight() - expectedWeight2 > ERROR_TOLERANCE ) {
                    System.err.println("Error in second feed weight for Chicken " + i);
                    System.err.println("\tActual: " + thisChicken.getWeight());
                    System.err.println("\tExpected: " + (expectedWeight2 ));
                }
            }

            if( thisChicken.getHeight() != heights[i] + 2 * HEIGHT_GAIN ) {
                System.err.println("Error in second feed height for Chicken " + i);
                System.err.println("\tActual: " + thisChicken.getHeight());
                System.err.println("\tExpected: " + (heights[i] + 2 * HEIGHT_GAIN ));
            }

            // TODO: test setName method
        }
        
		chickens[2] = chicken;

		// sort the chickens
		Arrays.sort(chickens);
		// print the chickens in sorted order (by height)
		for (Chicken c : chickens) {
			System.out.println(c);
		}
    }
}

/**
 * Demonstrates extension of a class that implements an interface.
 * Shows what happens if have a staticMethod -- inherited but not overridden.
 * Prints Car's static method
 */
public class Electric extends Car {
    
    /**
     * Creates an Electic car with a MPG of 200
     */
    public Electric() {
        super(200);
        tankSize = 0;
    }
    
    public int getTankSize() {
        System.out.println("Electric's getTankSize()");
        return tankSize;   
    }
    
    public static void main(String args[]) {
        Electric car = new Electric();
        car.move(1, 1);
        System.out.println(car);
        
        System.out.println(SPEED_LIMIT);
        System.out.println(car.getTankSize());
        System.out.println(staticMethod()); // calls Car's static method
    }
}

/**
 * Demonstrates extension of a class that implements an interface.
 * Shows what happens if have a staticMethod -- inherited but not overridden.
 */
public class Hybrid extends Car {
    
    /**
     * Creates a Hybrid car with a MPG of 45
     */
    public Hybrid() {
        super(45);
        tankSize = 10;
    }
    
    public static String staticMethod() {
        return "Hybrid's static method";
    }
    
    public int getTankSize() {
        System.out.println("Hybrid's getTankSize()");
        return tankSize;   
    }
    
    public static void main(String args[]) {
        Hybrid car = new Hybrid();
        car.move(1, 1);
        System.out.println(car);
        
        System.out.println(SPEED_LIMIT);
        System.out.println(car.getTankSize());
        System.out.println(staticMethod());
    }
}

public interface Movable {
	void move(double x, double y);
}

/**
 * Demonstrates how overloading works (static/compile-time resolution)
 * with some dynamic dispatch thrown in.
 */ 
public class OverloadPlay {

	public static void staticPrint(Parent parent) {
		System.out.println("Static Parent");
	}

	public static void staticPrint(Child child) {
		System.out.println("Static Child");
	}

	public void instancePrint(Parent parent) {
		System.out.println("Parent");
		parent.method();
	}

	public void instancePrint(Child child) {
		System.out.println("Child");
		child.method();
	}

	public static void main(String[] args) {
		Child child = new Child();
		Parent p = child;

		staticPrint(p);
		new OverloadPlay().instancePrint(p);
	}
}

class Parent {    
    public void method() {
        System.out.println("Called parent's method");   
    }
}

class Child extends Parent {
    public void method() {
        System.out.println("Called child's method");   
    }
}

public interface Powered extends Movable {
	double milesPerGallon();
	double SPEED_LIMIT = 95;
}