Consider the Rectangle class below. Create a Square class that extends the Rectangle class (but do not modify the Rectangle class). Do not define any additional attributes in the Square class; use the ones inherited from Rectangle. The Square class must implement a two-argument constructor whose first argument is the width/height of the square, while the second argument is the square's name. The Square class must override the toString() method so that it creates a String representation of the Square such that the String returned on calling the method returns something like: "Square s1: width=2.50, area=6.25, perimeter=10.00".
Use the Driver class below the Rectangle class to test your implementation.
/**
* This class represents a square
*/
public class Square extends Rectangle {
/*
* ctor - initializes the square to the specified size (same width and height)
*/
public Square(double size, String name) {
//Note: we can't access the Rectangle's private width and height variables to initialize ourselves:
// this.height = size; // illegal; height is private only to Rectangle
// this.width = size; // illegal; width is private only to Rectangle
// However, we can invoke Rectangle's public constructor, passing the same value for both our width and height.
// Note that we have to call the base class constructor as the VERY FIRST statement of our constructor.
super(size, size, name);
// this.name = name; // this would be legal here, but unnecessary since Rectangle's ctor already initialized name.
}
/**
* Create a String representation of this object
*/
public String toString() {
String s = String.format("Square %s: width=%#.2f, area=%#.2f, perimeter=%#.2f", name, this.getWidth(), this.computeArea(), this.computePerimeter());
//Note we could also call getHeight(), since that would return the same value.
//Note also that we could have omitted the "this" reference in the method calls; omitting them implies we're calling this object's methods
return s;
}
} // end class Square
/**
* This class represents a rectangle
*/
public class Rectangle {
private double width;
private double height;
protected String name;
/*
* ctor - initializes the rectangle to the specified width and height
*/
public Rectangle(double width, double height, String name) {
this.width = width;
this.height = height;
this.name = name;
}
/**
* @return the width
*/
public double getWidth() {
return width;
}
/**
* @param width the width to set
*/
public void setWidth(double width) {
this.width = width;
}
/**
* @return the height
*/
public double getHeight() {
return height;
}
/**
* @param height the height to set
*/
public void setHeight(double height) {
this.height = height;
}
/**
* computes the perimeter of this rectangle
* @return the perimeter
*/
public double computePerimeter() {
return 2*width + 2*height;
}
/**
* computes the area of this rectangle
* @return the area
*/
public double computeArea() {
return width * height;
}
/**
* Create a String representation of this object
*/
public String toString() {
String s = String.format("Rectangle %s: width=%#.2f, height=%#.2f, area=%#.2f, perimeter=%#.2f", name, width, height, computeArea(), computePerimeter());
return s;
}
}
// This is the DriverApp class that tests the Rectangle and Square classes
public class DriverApp {
/**
* @param args
*/
public static void main(String[] args) {
Rectangle r1 = new Rectangle( 3, 2, "r1");
System.out.println(r1);
Square s1 = new Square( 2.5, "s1");
System.out.println(s1);
}
}