Question

In Pl you will create an interface, Drawable, and an abstract class Polygon. The Point class is provided. Briefly go over the JavaDocs comments to see what is available to you. «interface Drawable +printToConsole(): void Polygon - points : List<Point> - colour : String Point + Polygon(String colour) + getPoints(): List<Point> + addPoint(Point p): void + equals(Object other): boolean +getArea(): double

Answer 1

Whether you face any problem or need any modification then share with me in the comment section, I'll happy to help you.

import java.util.ArrayList;

//Polygon class
public abstract class Polygon implements Drawable
{
   //private instance variable
   private ArrayList<Point> points;
   private String colour;
  
   /* Creates a Polygon with colour and ArrayList of Points */
   public Polygon(String colour)
   {
       this.colour = colour;
       points = new ArrayList<>();
   }
  
   /* method returns the points */
   public ArrayList<Point> getPoints()
   {
       return points;
   }
  
   /* method to add a Point p to the points list */
   public void addPoint(Point p)
   {
       points.add(p);
   }
  
   @Override
   public boolean equals(Object other)
   {
       //if both objects are the same
       if(this == other)
           return true;
      
       //if other is not a Polygon they cannot be equal
       if(!(other instanceof Polygon))
           return false;
      
       //convert to Polygon
       Polygon poly = (Polygon)other;
      
       //if colour is not equals to this Polygon
       if(!colour.equals(poly.colour))
           return false;
      
       //if number of Points is not equals to this Polygon
       if(points.size() != poly.points.size())
           return false;
      
       //check for all the Points in list
       for(int i=0; i<points.size(); i++)
       {
           //if Point is not equal
           if(points.get(i) != poly.points.get(i))
               return false;
       }
       //return true if both objects are the same
       return true;
   }
  
   //abstract method to return area of the Polygon
   public abstract double getArea();
}