(The Triangle class) Design a class named Triangle that extends GeometricObject. The class contains:

/*********************************************************************************
* (The Triangle class) Design a class named Triangle that extends                *
* GeometricObject. The class contains:                                           *
* ■ Three double data fields named side1, side2, and side3 with default          *
*   values 1.0 to denote three sides of the triangle.                            *
* ■ A no-arg constructor that creates a default triangle.                        *
* ■ A constructor that creates a triangle with the specified side1, side2, and   *
*   side3.                                                                       *
*                                                                                *
* ■ The accessor methods for all three data fields.                              *
* ■ A method named getArea() that returns the area of this triangle.             *
* ■ A method named getPerimeter() that returns the perimeter of this triangle.   *
* ■ A method named toString() that returns a string description for the triangle.*
*                                                                                *
* For the formula to compute the area of a triangle, see Programming Exercise    *
* 2.19. The toString() method is implemented as follows:                         *
*                                                                                *
* return "Triangle: side1 = " + side1 + " side2 = " + side2 +                    *
* " side3 = " + side3;                                                           *
*                                                                                *
* Draw the UML diagrams for the classes Triangle and GeometricObject and         *
* implement the classes. Write a test program that prompts the user to enter     *
* three sides of the triangle, a color, and a Boolean value to indicate whether  *
* the triangle is filled. The program should create a Triangle object with these *
* sides and set the color and filled properties using the input. The program     *
* should display the area, perimeter, color, and true or false to indicate       *
* whether it is filled or not.                                                   * 
*********************************************************************************/
import java.util.Scanner;

public class Exercise_11_01 {
	public static void main(String[] args) {
		// Create a Scanner object
		Scanner input = new Scanner(System.in);

		// Prompt the user to enter three sides of the triangle
		System.out.print("Enter three side of the triangle: ");
		double side1 = input.nextDouble();		
		double side2 = input.nextDouble();		
		double side3 = input.nextDouble();

		// Prompt the user to enter a color
		System.out.print("Enter a color: ");
		String color = input.next();

		// Prompt the user to enter whether the triangle is filled
		System.out.print("Is the triangle filled (true / false)? ");
		boolean filled = input.nextBoolean();

		// Create triangle object with user input
		Triangle triangle = new Triangle(side1, side2, side3);
		triangle.setColor(color);
		triangle.setFilled(filled);

		System.out.println(triangle.toString());
		System.out.println("Area: " + triangle.getArea());
		System.out.println("Perimeter: " + triangle.getPerimeter());
		System.out.println("Color: " + triangle.getColor());
		System.out.println("Triangle is" + (triangle.isFilled() ? "" : " not ") 
			+ "filled");
	}
}

GeometricObject.java 

/************************************
* GeometricObject                   *
*-----------------------------------*
* -color: String                    *
* -filled: boolean                  *
* -dateCreated: java.util.Date      *
*-----------------------------------*
* +GeometricObject()                *
* +GeometricObject(color: String,   *
*	filled: boolean)                 *
* +getColor(): String               *
* +setColor(color: Stirng): void    *
* +isFilled(): boolean              *
* +setFilled(filled: boolean): void *
* +getDateCreated(): java.util.Date *
* +toString(): String               *
************************************/

// Implement GeometricObject class
public class GeometricObject {
	private String color = "white";
	private boolean filled;
	private java.util.Date dateCreated;

	/** Construct a default geometric object */
	public GeometricObject() {
		dateCreated = new java.util.Date();
	}

	/** Construct a geometric object with the specified color
	  * and filled value */
	public GeometricObject(String color, boolean filled) {
		dateCreated = new java.util.Date();
		this.color = color;
		this.filled = filled;
	}

	/** Return colot */
	public String getColor() {
		return color;
	}

	/** Set a new color */
	public void setColor(String color) {
		this.color = color;
	}

	/** Return filled. Since filled is boolean,
		its getter method is named isFilled */
	public boolean isFilled() {
		return filled;
	}

	/** Set a new filled */
	public void setFilled(boolean filled) {
		this.filled = filled;
	}

	/** Get dateCreated */
	public java.util.Date getDateCreated() {
		return dateCreated;
	}

	/** Return a string representation of this object */
	public String toString() {
		return "created on " + dateCreated + "\ncolor: " + color + 
			" and filled: " + filled;
	}
}

Triangle.java 

/*********************************************************
*                       Triangle                         *
*--------------------------------------------------------*
* -side1: double                                         *
* -side2: double                                         *
* -side3: double                                         *
* +Triangle()                                            *
* +Triangle(side1: double, side2: double, side3: double) *
* +getSide1(): double                                    *
* +getSide2(): double                                    *
* +getSide3(): double                                    *
* +getArea(): double                                     *
* +getPerimeter(): double                                *
* +toString(): String                                    *
*********************************************************/

// Implement Triangle class
public class Triangle 
		extends GeometricObject {
	private double side1;
	private double side2;
	private double side3;

	/** Construct default Triangle object */
	Triangle() {
		side1 = side2 = side3 = 1.0;
	}

	/** Construct a triangle with specified side1, side2 and side3 */
	Triangle(double side1, double side2, double side3) { 
		this.side1 = side1;
		this.side2 = side2;
		this.side3 = side3;
	}

	/** Return side1 */
	public double getSide1() {
		return side1;
	}

	/** Return side2 */
	public double getSide2() {
		return side2;
	}

	/** Return side3 */
	public double getSide3() {
		return side3;
	}

	/** Return area of this triangle */
	public double getArea() {
		double s = (side1 + side2 + side3) / 2;
		return Math.sqrt(s * (s - side1) * (s - side2) * (s - side3));
	}

	/** Return perimeter of this triangle */
	public double getPerimeter() {
		return side1 + side2 + side3;
	}

	/** Return a string description for the triangle */
	public String toString() {
		return "Triangle: side1 = " + side1 + " side2 = " + side2 +
			" side3 = " + side3;
	}
}