Question

Write a JavaFX application that displays 10,000 very small circles (radius of 1 pixel) in random locations within the visible area. Fill the dots on the left half of the scene red and the dots on the right half of the scene green. Use the getWidth method of the scene to help determine the halfway point.

This is what I have so far:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.shape.Circle;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import java.util.Random;
import javafx.scene.Group;

public class Class615 extends Application
{

@Override
public void start(Stage primaryStage)
{
Group root = new Group();
Random gen = new Random();
Color circleColor = Color.RED;
Color fill = null;
final int radius = 1;

for (int count = 1; count <= 10000; count++)
{
double x = gen.nextInt(1) + 2;
double y = gen.nextInt(1) + 2;
  
Circle circle = new Circle(x, y, radius);
circle.setStroke(Color.WHITE);
circle.setFill(fill);
circle.getCenterX();
double xLocate = circle.getCenterX();
root.getChildren().add(circle);
  
if (xLocate < 150)
{
fill = circleColor;
} else
{
fill = Color.GREEN;
}
  
}

Scene scene = new Scene(root, 300, 250, Color.BLACK);

primaryStage.setTitle("Circles");
primaryStage.setScene(scene);
primaryStage.show();
}

public static void main(String[] args)
{
launch(args);
}

}

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

// Class615.java

import javafx.application.Application;

import javafx.scene.Scene;

import javafx.scene.shape.Circle;

import javafx.scene.paint.Color;

import javafx.stage.Stage;

import java.util.Random;

import javafx.scene.Group;

public class Class615 extends Application {

    @Override

    public void start(Stage primaryStage) {

        Group root = new Group();

        Random gen = new Random();

        final int radius = 1;

        //creating a Scene

        Scene scene = new Scene(root, 300, 250, Color.BLACK);

        //looping for 10000 times

        for (int count = 1; count <= 10000; count++) {

            //generating a random x coordinate between 0 and scene.getWidth()

            double x = gen.nextInt((int) scene.getWidth());

            //generating a random y coordinate between 0 and scene.getHeight()

            double y = gen.nextInt((int) scene.getHeight());

            //creating a Circle at this position

            Circle circle = new Circle(x, y, radius);

            //using no stroke

            circle.setStroke(null);

            //checking if x is on left half or right half

            if (x < scene.getWidth() / 2) {

                //left half, using red as fill color

                circle.setFill(Color.RED);

            } else {

                //using green as fill color

                circle.setFill(Color.GREEN);

            }

            //adding circle to the scene

            root.getChildren().add(circle);

        }

        primaryStage.setTitle("Circles");

        primaryStage.setScene(scene);

        primaryStage.show();

    }

    public static void main(String[] args) {

        launch(args);

    }

}

/*OUTPUT*/