JavaFX Circle calculate distance between two circles

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class Main extends Application {
   @Override//from www.j  av  a 2 s .  c  o  m
   public void start(Stage primaryStage) {
      // Create a pane
      Pane pane = new Pane();

      // Create two circles
      Circle circle1 = new Circle(Math.random() * 201, Math.random() * 201, 15);
      Circle circle2 = new Circle(Math.random() * 201, Math.random() * 201, 15);

      // Create a line
      Line line = new Line(circle1.getCenterX(), circle1.getCenterY(), circle2.getCenterX(), circle2.getCenterY());

      // Calculate distance between the two centers of the circles
      double distance = Math
            .sqrt(Math.pow(line.getEndX() - line.getStartX(), 2) + Math.pow(line.getEndY() - line.getStartY(), 2));

      // Create a text
      double x = (line.getStartX() + line.getEndX()) / 2;
      double y = (line.getStartY() + line.getEndY()) / 2;
      Text text = new Text(x, y, String.valueOf(distance));

      // Add nodes to pane
      pane.getChildren().addAll(circle1, circle2, line, text);

      // Create a scene and place it in the stage
      Scene scene = new Scene(pane);
      primaryStage.setTitle("java2s.com");
      primaryStage.setScene(scene);
      primaryStage.show();
   }
}