Here is my assignment that I need help with:
1. Implement a class IrregularPolygon that contains an array list of Point2D.Double objects.
2. The Point2D.Double class defines a point specified in double precision representing a location in (x, y) coordinate space. For example, Point2D.Double(2.5, 3.1) constructs and initializes a point at coordinates (2.5, 3.1).
3. Use the following declarations as a starting point for your lab work.
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import java.awt.geom.*; // for Point2D.Double
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import java.util.ArrayList; // for ArrayList
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import gpdraw.*; // for DrawingTool
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public class IrregularPolygon{
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private ArrayList <Point2D.Double> myPolygon;
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// constructors
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public IrregularPolygon() { }
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// public methods
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public void add(Point2D.Double aPoint) { }
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public void draw() { }
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public double perimeter() { }
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public double area() { }
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}
As far as I can tell, I am ALMOST there, but there seems to be a technicality in my main method that prevents my program from working. Here is the tester file:
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import java.awt.geom.*;
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import java.util.Scanner;
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public class IrregularPolygonTester
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{
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public static String blah = new String("Y");//is this the proper way to do this?
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public static void main(String[] args)
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{
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IrregularPolygon myShape = new IrregularPolygon();
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Scanner in = new Scanner(System.in);
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while(blah.equals("Y"))//test if user wants to keep adding points
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{
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System.out.print("Enter X-Coordinate: ");
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double x = in.nextDouble();
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System.out.print("Enter Y-Coordinate: ");
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double y = in.nextDouble();
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Point2D.Double myPoint = new Point2D.Double(x, y);
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myShape.toAdd(myPoint);//this line is causing problems
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System.out.print("Enter another point? (Y/N)");
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blah = in.nextLine();
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blah.toUpperCase();
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blah.trim();
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}
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myShape.draw();
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System.out.println("Perimeter of figure = " + myShape.perimeter());
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System.out.println("Area of figure = " + myShape.area());
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}
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}
And here is the regular class file:
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import java.awt.geom.*;
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import java.util.ArrayList;
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import gpdraw.*;
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public class IrregularPolygon
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{
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private ArrayList <Point2D.Double> myPolygon;
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private double x;
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private double y;
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private double perim;
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private double total;
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private DrawingTool myPen;
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private SketchPad myPaper;
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public IrregularPolygon()
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{
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ArrayList <Point2D.Double> myPolygon = new ArrayList <Point2D.Double>();
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x = 1;
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y = 1;
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perim = 0.0;
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total = 0.0;
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myPaper = new SketchPad(500,500);
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myPen = new DrawingTool(myPaper);
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}
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public void toAdd(Point2D.Double myPoint)
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{
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myPolygon.add(myPoint);
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}
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public void draw()
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{
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myPen.up();
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myPen.move(myPolygon.get(0).getX(), myPolygon.get(0).getY());
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myPen.down();
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for(int i = 1; i < myPolygon.size(); i++)
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{
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myPen.move(myPolygon.get(i).getX(), myPolygon.get(i).getY());
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}
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}
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public double perimeter()
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{
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for(int i = 0; i < myPolygon.size(); i++)
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{
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perim += ((Point2D.Double)myPolygon.get(i)).distance((Point2D.Double)myPolygon.get(i + 1));
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}
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return perim;
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}
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public double area()
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{
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for(int i = 0; i < myPolygon.size(); i++)
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{
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double X1 = (myPolygon.get(i).getX());
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double Y1 = (myPolygon.get(i).getY());
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double X2 = (myPolygon.get(i + 1).getX());
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double Y2 = (myPolygon.get(i + 1).getY());
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total += (X1 * Y2 - Y1 * X2);
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}
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return 0.5 * total;
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}
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}
ANY help would be greatly appreciated! If you need any additional info, please let me know! Thanks in advance!
