Homework 9

Homework 9

1. Circle class (10 points)
Define and implement a class called Circle which has the following instance variable, constructors and methods.
Instance Variable:

private double radius - the radius of the Circle object.

Constructors:

public Circle() - default constructor which sets the radius of the Circle object to one (unit circle).
public Circle(double radius) - constructor which sets the radius of the Circle object to the specified value.

Methods:
public double getRadius() - accessor method which returns the radius of the Circle object.
public void setRadius(double radius) - mutator method which sets the radius of the Circle object to the specified value.
public double getArea() - method which calculates and returns the area of the Circle object.
public double getCircumference() - method which calculates and returns the circumference of the Circle object.
public String toString() - method which returns a String containing the radius, circumference and area of the Circle object in the following format:
    radius        = 4.0
    circumference = 25.132741228718345
    area          = 50.26548245743669
    
public boolean equals(Circle c) - method which returns true if the radius of the [calling] Circle object is equal to the radius of the passed [parameter] Circle object, false otherwise.
public static double area(double radius) - static method calculates and returns the area of a circle with the specified radius.
public static double circumference(double radius) - static method calculates and returns the circumference of a circle with the specified radius.
NOTES:

Both the getArea and getCircumference methods must use the respective static methods to calculate the area and circumference.
You must use the value of p stored in the Math class (i.e. Math.PI).

2. Cylinder class (10 points)
Define and implement a class called Cylinder which has the following instance variables, constructors and methods.
Instance Variables:

private double length - the length of the Cylinder object.
private Circle circle - stores the radius of the Cylinder object.

Constructors:

public Cylinder() - default constructor which sets both the diameter (= radius*2) and length of the Cylinder object to one.
public Cylinder(double diameter, double length) - constructor which sets the diameter and length of the Cylinder object to the specified values.

Methods:
public double getDiameter() - accessor method which returns the diameter of the Cylinder object.
public void setDiameter(double diameter) - mutator method which sets the diameter of the Cylinder object to the specified value.
public double getLength() - accessor method which returns the length of the Cylinder object.
public void setLength(double length) - mutator method which sets the length of the Cylinder object to the specified value.
public Circle getCircle() - accessor method which returns the circle instance variable for the Cylinder object.
public double getVolume() - method which calculates and returns the volume of the Cylinder object.
public double getSurfaceArea() - method which calculates and returns the surface area of the Cylinder object.
public String toString() - method which returns a String containing the diameter, length, surface area and volume of the Cylinder object in the following format:
    diameter     = 4.0
    length       = 2.0
    surface area = 37.6991118431
    volume       = 25.1327412287
    
public boolean equals(Cylinder c) - method which returns true if the diameter (or radius) and length of the [calling] Cylinder object is equal to the diameter (or radius) and length of the passed [parameter] Cylinder object, false otherwise.
NOTES:

The diameter of the Cylinder object should be stored (as a radius) in the circle instance variable, which is a Circle object!.
Utilize the methods available with the Circle object to make implementing the methods for the Cylinder class easier. Most of the methods should be implemented in one line!

3. Pipe class (10 points)
Define and implement a class called Pipe which is derived from the Cylinder class and has the following instance variable, constructor and methods.
Instance Variable:

private boolean isThreaded - true if the Pipe object is threaded, false otherwise

Constructor:

public Pipe(double diameter, double length, boolean isThreaded) - constructor which sets the diameter, length and thread state of the Pipe object to the specified values.

Methods:
public boolean isThreaded() - method which returns the value of the isThreaded instance variable.
public void thread() - method which sets the value of the isThreaded instance variable to true.
public void getSurfaceArea() - method which calculates and returns the surface area of the Pipe object.
public String toString() - method which returns a String containing the diameter, length, surface area, volume and thread state of the Pipe object in the following format:
    diameter     = 4.0
    length       = 2.0
    surface area = 37.6991118431
    volume       = 50.2654824574
    threaded     = true
    
public boolean equals(Pipe p) - method which returns true if the diameter (or radius), length and thread state of the [calling] Pipe object is equal to the diameter (or radius), length and thread state of the passed [parameter] Pipe object, false otherwise.
NOTES:

Most, if not all, of the constructor and method implementations should be one line. Take advantage of the inherited methods and parent constructors when applicable.
You must override the getSurfaceArea method inherited from the Cylinder class, since the surface area of a pipe is differnt than that of a cylinder (i.e. a pipe is a hollow cylinder).
Assume the thickness of the pipe is infintesimally small.

4. PipeTest class (5 points)
Define and implement a class called PipeTest which demonstrates the complete functionality of only the Pipe class.
NOTES:

To demonstrate the functionality of the toString method, simply pass the Pipe object to the System.out.println method. This will result in the toString method of the passed Pipe object being called and it's return value being printed to the screen.