created circle adapter

src/main/java/ca/uwaterloo/cs446/designpatterns/adapter/AdapterMain.java

@@ -8,11 +8,13 @@ public static void main(String[] args) {
 		// Old objects
 		Line line = new Line();
 		Rectangle rectangle = new Rectangle();
+		Circle circle = new Circle();
 
 		// Adapt them with adapters
 		List<Shape> shapes = new ArrayList<Shape>();
 		shapes.add(new LineAdapter(line));
 		shapes.add(new RectangleAdapter(rectangle));
+		shapes.add(new CircleAdapter(circle));
 
 		// Code can now operate using common interface
 		int x1 = 7;

src/main/java/ca/uwaterloo/cs446/designpatterns/adapter/CircleAdapter.java

@@ -0,0 +1,20 @@
+package ca.uwaterloo.cs446.designpatterns.adapter;
+
+public class CircleAdapter implements Shape {
+   private Circle adaptee;
+
+   public CircleAdapter(Circle circle) {
+       this.adaptee = circle;
+   }
+
+   @Override
+   public void draw(int x1, int y1, int x2, int y2) {
+       // Center is the difference between the two points
+       int centerX = (Math.max(x1, x2) - Math.min(x1, x2)) / 2;
+       int centerY = (Math.max(y1, y2) - Math.min(y1, y2)) / 2;
+
+       // radius is the minimum distance between x and y
+       int radius = Math.min(Math.abs(x1 - x2), Math.abs(y1 - y2));
+       adaptee.draw(centerX, centerY, radius);
+   }
+}