Question

Objective

Extend the class GeometicShapes to include a Triangle class..

Background Reading

ZyBooks Chapter 10

Task

Create the following fields and methods for a Triangle class that extends the provided GeometricShapes class

public class GeometricShapes
{
private String color = "red";
private boolean filled;
private java.util.Date dateCreated;
  
public GeometricShapes()
{
dateCreated = new java.util.Date();
}
  
public GeometricShapes(String color, boolean filled)
{
dateCreated = new java.util.Date();
this.color = color;
this.filled = filled;
}
  
public void setColor (String color)
{
this.color = color;
}
  
public String getColor ()
{
return color;
}
public void setFilled (boolean filled)
{
this.filled = filled;
}
  
public boolean getFilled ()
{
return filled;
}

  
}

1. Declare three double data fields named side1, side2, and side3. Set the default value of the fields to 1.0. These fields represent the three sides of the triangle.

2. Write a no argument constructor that creates a triangle with the default values..

3. Write a constructor that creates a triangle with values specified for side1, side2, and side3.

4. Write public accessor methods for all three sides..

5. Write public mutator methods for all three sides.

6. Write a public method getArea() with no parameters that returns the area of this triangle.

7. Write a public method getPerimeter() with no parameters that returns the perimeter of this triangle.`.

8. Overrirde the toString() method to read as follows:

   return "Triangle: side1 = " + side1 + " side2 = " + side2 + " side3 = " + side3 + " filled = " + filled + " color = " + color;

9. I have my code now but I only got 15/40 could you please correct for me?

import java.lang.Math; // this library is used for sqrt function in getArea() method
//This class remains the same
class GeometricShapes
{
private String color = "red";
private boolean filled;
private java.util.Date dateCreated;
  
public GeometricShapes()
{
dateCreated = new java.util.Date();
}
  
public GeometricShapes(String color, boolean filled)
{
dateCreated = new java.util.Date();
this.color = color;
this.filled = filled;
}
  
public void setColor (String color)
{
this.color = color;
}
  
public String getColor ()
{
return color;
}
public void setFilled (boolean filled)
{
this.filled = filled;
}
  
public boolean getFilled ()
{
return filled;
}
}
// Triangle class estends the GeometricShapes class
class Triangle extends GeometricShapes
{
private double side1, side2, side3;
// default constructor for assigning default values
//set color to red and filled to false
public Triangle()
{
side1 = 1;
side2 = 1;
side3 = 1;
setColor("red");
setFilled(false);
}
//parameterized constructor for setting the given values
public Triangle(double s1, double s2, double s3, String color, boolean f)
{
super(color,f);
side1 = s1;
side2 = s2;
side3 = s3;
}
//getter function to obtain the sides
public double getSide1()
{
return side1;
}
public double getSide2()
{
return side2;
}
public double getSide3()
{
return side3;
}
//setter functions for sides
public void setSide1(double s)
{
side1 = s;
}
public void setSide2(double s)
{
side2 = s;
}
public void setSide3(double s)
{
side3 = s;
}
//returns the perimeter
public double getPerimeter()
{
return (side1+side2+side3);
}
//returns the area
public double getArea()
{
double s = getPerimeter()/2;
return (Math.sqrt(s*(s-side1)*(s-side2)*(s-side3)));
}
//returns the string of values
public String toString()
{
return "Triangle: \nside1 = " + side1 + " \nside2 = " + side2 + "\nside3 = " + side3 + "\nfilled = " + getFilled() + "\ncolor = " + getColor();
}

public static void main(String args[]){

//a Triangle object with default constructor
Triangle t = new Triangle();
System.out.println(t.toString());
System.out.println("Perimeter is: "+ t.getPerimeter());
System.out.println("Area is: "+ t.getArea());
}
}

Answer 1

I have answered many different versions of this question before. Without knowing your test code, I can not guarantee that this solution would work 100%, but in some of the previous questions, the constructor taking side values must validate the sides confirming that the three sides constitute a valid triangle. May be that is the case here. So try this code, and if it is not working, please provide the test code /test suite or whatever thing you are using to run this code, I’ll help.

Here is the completed code for Triangle class. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

// Triangle class

package geometricobj;

public class Triangle extends GeometricObject {

      // attributes

      private double side1;

      private double side2;

      private double side3;

      // default constructor, initializes fields to 1.0

      public Triangle() {

            this(1.0, 1.0, 1.0);

      }

      // constructor taking values for all three sides

      public Triangle(double side1, double side2, double side3)

                  throws IllegalArgumentException {

            // validating the sides

            if (side1 > 0

                        && side2 > 0

                        && side3 > 0

                        && ((side1 + side2 > side3) || (side2 + side3 > side1) || (side1

                                    + side3 > side2))) {

                  this.side1 = side1;

                  this.side2 = side2;

                  this.side3 = side3;

            } else {

                  // these three sides cannot form a valid traingle, so throwing

                  // exception

                  throw new IllegalArgumentException("Invalid sides for triangle: ("

                              + side1 + ", " + side2 + ", " + side3 + ")");

            }

      }

      // parameterized constructor for setting the values including super class

      // attributes

      public Triangle(double s1, double s2, double s3, String color, boolean f) {

            // invoking other constructor

            this(s1, s2, s3);

            setColor(color);

            setFilled(f);

      }

      // setters

      public void setSide1(double side1) {

            this.side1 = side1;

      }

      public void setSide2(double side2) {

            this.side2 = side2;

      }

      public void setSide3(double side3) {

            this.side3 = side3;

      }

      // getters

      public double getArea() {

            double s = getPerimeter() / 2;

            return Math.sqrt(s * (s - side1) * (s - side2) * (s - side3));

      }

      // get perimeter

      public double getPerimeter() {

            return side1 + side2 + side3;

      }

      // override toString

      public String toString() {

            return "Triangle: side1 = " + side1 + " side2 = " + side2 + " side3 = "

                        + side3 + " filled = " + isFilled() + " color = " + getColor();

      }

}