Add Ex 18.20

Author: jsquared21

Exercise_18/Exercise_18_20/Exercise_18_20.class

@@ -0,0 +1,41 @@
+/*********************************************************************************
+* (Display circles) Write a Java program that displays ovals, as shown in Figure *
+* 18.12b. The circles are centered in the pane. The gap between two adjacent     *
+* circles is 10 pixels, and the gap between the border of the pane and the       *
+* largest circle is also 10.                                                     *
+*********************************************************************************/
+import javafx.application.Application;
+import javafx.stage.Stage;
+import javafx.scene.Scene;
+import javafx.scene.layout.StackPane;
+import javafx.geometry.Insets;
+import javafx.scene.shape.Circle;
+import javafx.scene.paint.Color;
+
+public class Exercise_18_20 extends Application {
+	protected static StackPane pane = new StackPane();
+
+	@Override // Override the start method in the Application class
+	public void start(Stage primaryStage) {
+		int numberOfCircles = 16; // Number of ovals
+		addCircles(numberOfCircles);
+		pane.setPadding(new Insets(10, 10, 10, 10));
+
+		// Create a scene and place it in the stage
+		Scene scene = new Scene(pane);
+		primaryStage.setTitle("Exercise_18_20"); // Set the stage title
+		primaryStage.setScene(scene); // Place the scene in the stage
+		primaryStage.show(); // Display the stage
+	}
+
+	/** Method adds n circles to pane recursively */
+	public static void addCircles(int n) {
+		if (n > 0) {
+			Circle circle = new Circle(10 * n);
+			circle.setFill(Color.WHITE);
+			circle.setStroke(Color.BLACK);
+			pane.getChildren().add(circle);
+			addCircles(n - 1); // Recursive call
+		}
+	}
+}