1. ./Chicken.java
2. ./NotTheChickenClass.java

/**
 * A Java class that represents a chicken. The state of the chicken is
 * its name, height and weight.  
 *
 * Difference from previous version: added overloaded constructor and
 * overriden toString and equals methods.
 * 
 * @author Sara Sprenkle
 */
public class Chicken {

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

    /** the name of the chicken */
    private String name;

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

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

    /**
     * Constructs a new Chicken object with the charactistics as specified 
     * by the parameters.
     * @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 = name;
        this.height = height;
        this.weight = weight;
    }

    /**
     * Constructs a new Chicken object with the default name "Bubba".
     * height and weight specified by parameters
     * @param height the height of the chicken in centimeters
     * @param weight the weight of the chicken in pounds
     */
    public Chicken(int height, double weight) {
        // if the user doesn't specify a name, let's make it Bubba
        this("Bubba", height, weight);
    }

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

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

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

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

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

    /**
     * Feeds the chicken, increasing the chicken's weight and height
     */
    public void feed() {
        weight += .3;
        height += 1;
    }

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

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

    /**
     * Returns a string representation of the chicken.
     * Format:
     * <br/>Chicken name: &lt;name&gt;
     * <br/>\tweight: &lt;weight&gt; pounds
     * <br/>\theight: &lt;height&gt; cm
     * <p>Weight is displayed to one decimal place
     *
     * @return a string representation of this Chicken
     */
    @Override
    public String toString() {
        // Use a StringBuilder: more efficient than concatenating strings.
        StringBuilder rep = new StringBuilder("Chicken name: ");
        rep.append(name);
        rep.append("\n\tweight: ");
        rep.append(String.format("%.1f", weight)); // guesses as to what this does?
        rep.append(" pounds\n");
        rep.append("\theight: ");
        rep.append(height);
        rep.append(" cm");
        return rep.toString();
    }

    /**
     * Determines if the Object o is equivalent to this Chicken, 
     * based on their name, height, and weight.
     *
     * @param o the object to compare
     * @return true if this object is the same as the o argument (by name, height, and wight).  Otherwise, returns false. 
     */
    @Override
    public boolean equals(Object o) {
        // Follows the _Effective Java_ process
        if( o == this ) {
            return true;
        }

        if( ! ( o instanceof Chicken ) ) {
            return false;
        }

        Chicken other = (Chicken) o;

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

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

        if( Double.compare( other.getWeight(), this.getWeight()) == 0 ) {
            return true;
        }

        // if the weight is close enough, let's consider them
        // equivalent
        double difference = this.getWeight() - other.getWeight();
        if(  difference > -.0001 && difference < .0001  ) {
            return true;   
        }

        return false;
    }

    /**
     * Tests the Chicken class
     * @param args the command-line arguments
     */
    public static void main(String[] args) {
        int fredHeight = 38;
        Chicken chicken = new Chicken("Fred", fredHeight, 2.0);

        System.out.println(chicken);

        chicken.feed();

        int newFredHeight = chicken.getHeight();

        System.out.println();
        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");

        System.out.println("\nLook at this beautiful formatting: ");
        System.out.println(chicken);

        String expectedRep = "Chicken name: Fred\n\tweight: 2.6 pounds\n\theight: 40 cm";
        String actualRep = chicken.toString();

        // Test the toString method
        // 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;

        // Test equals method
        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);
        // Works because we have some error tolerance in weight comparison
        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};
        String[] newNames = {"Rocky II", "Chicken"};

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

            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] + .3 ) {
                System.err.println("Error in feed weight for Chicken " + i);
                System.err.println("\tActual: " + thisChicken.getWeight());
                System.err.println("\tExpected: " + (weights[i] + .3) );
            }

            if( thisChicken.getHeight() != heights[i] + 1 ) {
                System.err.println("Error in feed height for Chicken " + i);
                System.err.println("\tActual: " + thisChicken.getHeight());
                System.err.println("\tExpected: " + (heights[i] + 1) );
            }

            // 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 * .3;
            int comparison = Double.compare(thisChicken.getWeight(),  expectedWeight2 );
            if( comparison != 0 ) {
                if( thisChicken.getWeight() - expectedWeight2 > .0001 ) {
                    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 * 1 ) {
                System.err.println("Error in second feed height for Chicken " + i);
                System.err.println("\tActual: " + thisChicken.getHeight());
                System.err.println("\tExpected: " + (heights[i] + 2 * 1 ));
            }
            
            thisChicken.setName(newNames[i]);
            
            if( !thisChicken.getName().equals(newNames[i]) ) {
                System.err.println("Problem likely in setName");
                System.err.println("\tActual: " + thisChicken.getName());
                System.err.println("\tExpected: " + newNames[i]);
            }

        }
        
        // ---  Test when equals should return false ---
        
        Chicken[] notQuiteFreds = new Chicken[3];
        notQuiteFreds[0] = new Chicken("fred", 40, 2.6);
        notQuiteFreds[1] = new Chicken("Fred", 39, 2.6);
        notQuiteFreds[2] = new Chicken("Fred", 40, 2.7);
        
        for( int i=0; i < notQuiteFreds.length; i++ ) {
            // expect that equals is false for all cases
            if( chicken.equals(notQuiteFreds[i] ) ) {
                 System.err.println("Problem likely in equals");
                 System.err.println("\tFred: " + chicken);
                 System.err.println("\tNot Fred: " + notQuiteFreds[i]);
            }
        }

    }
}

/**
 * Demonstrates how we can create Chicken objects 
 * and call its public methods, but
 * we can't call the Chicken's private methods.
 * (This class will NOT compile.)
 * 
 * @author Sara Sprenkle
 */ 
public class NotTheChickenClass {
    
    public static void main(String[] args) {
    
        Chicken myChicken = new Chicken("Fred", 10, 2);
        
        myChicken.feed();
        
        // this will result in a compiler error:
        myChicken.privateMethod();
    
    }

}