Help with errors and questions

Hey Guys,

So I recently got a a project from my teacher.

Its on a shape. />/>/>/>

Great.

This is what Im working with



Just a little background info.
We are to assume that a rhombus is created with its top and bottom corners at the same x coordinate, and its left and y corners at the same y coordinate

The point that defines the (x, y) coordinate of its top corner.
The length of its horizontal diagonal is the p
The length of its vertical diagonal is the q
Once we’ve got the 4 points, the length of its horizontal diagonal, and the length of its vertical diagonal,
we can calculate all the properties of the rhombus.

Now to the good stuff.
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I created three different classes:Rhombus,RhombusTester, and TestDriver.
Please read the comments

package edu.westga.rhombus.model;

import java.awt.geom.Point2D;

//Class defines a Rhombus with three different points. From points 
//these points an (x,y) coordinate is calculated from the corners
//of the Rhombus

public class Rhombus {
	
	//Instance variables represents three different points from the
	//Rhombus. The top point, the point that defines the horziontal
	//length and the point that defines the vertical length
	Double topPoint;
	Double hLength;
	Double vLength;
	
	
	public Rhombus(double topPoint, double hLength, double vLength)
	{
		
	}

	public double getTopPoint()
	{
		return topPoint; // My instructor require I return a Point2D.Double
						//Im not sure how I go about that.
	}
}

Instructions: In class Rhombus:
1. Implement the constructor with its 3 parameters (top point, horizontal length, and
vertical length), and declare and initialize the instance variables.
2. Implement accessor method getTopPoint, which takes no parameters and returns a
Point2D.Double.

Im having trouble understanding the return part, so i just put topPoint as the return.

Next,

package edu.westga.rhombus.controller;

public class RhombusTester {

		Double topPoint;
	public RhombusTester()// Im pretty sure these needs a paramter 
						 // My teacher used Point2D.Double as a
						//type in his example, But below its not working.
	{
		topPoint= new Point2D.Double(4.0,6.5);//It gives an error
											  //saying Point2D.Double cant be
											  //resolved to a type
	}
	
	public void testRhombus()
	{
		System.out.println("The Expected Value of the top point is");
		topPoint.getX();// It gives an error saying getX() is undefined for
						//the type double
		
		//topPointX= topPoint.getX();
		
	}
}

Instructions:In class RhombusTester:
1. Implement method testRhombus, a void method with no parameters, and the
instance variable it needs to do its job.
In the method’s body, display the expected and actual x, y values of the top point of the
rhombus.
- Note: class Point2D.Double defines accessor methods getX and getY.
2. Implement the constructor to initialize the instance variable.

Obviously Point2D.Double is not a type because when I tried to declare topPoint with type Point2D.Double it says its not a type. But to my instructor it is.

He insisted : To define a point in Java, use class Point2D.Double, which is documented at
http://docs.oracle.com/javase/7/docs/api/java/awt/geom/Point2D.Double.html.

o For example, to create a Point2D.Double variable named topPoint at 4.0, 6.5:
topPoint = new Point2D.Double(4.0, 6.5);


I need a clear understanding, Im pretty puzzled.

Thanks,

sad ladyJava