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Commit 6da47c5

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Add ch 15 solutions for ex 17, 18, 19.
1 parent 5a9d01f commit 6da47c5

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4 files changed

+267
-2
lines changed

4 files changed

+267
-2
lines changed

‎ch_09/exercise09_06/StopWatch.java‎

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Original file line numberDiff line numberDiff line change
@@ -48,14 +48,14 @@ public StopWatch() {
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/**
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* ■しかく A method named start() that resets the startTime to the current time.
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*/
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void start() {
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publicvoid start() {
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startTime = System.currentTimeMillis();
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}
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/**
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* ■しかく A method named stop() that sets the endTime to the current time.
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*/
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void stop() {
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publicvoid stop() {
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endTime = System.currentTimeMillis();
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}
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‎ch_15/Exercise15_17.java‎

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package ch_15;
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import javafx.application.Application;
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import javafx.collections.ObservableList;
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import javafx.geometry.Insets;
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import javafx.scene.Node;
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import javafx.scene.Scene;
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import javafx.scene.control.Label;
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import javafx.scene.input.MouseButton;
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import javafx.scene.layout.Pane;
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import javafx.scene.layout.VBox;
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import javafx.scene.paint.Color;
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import javafx.scene.shape.Circle;
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import javafx.scene.shape.Rectangle;
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import javafx.stage.Stage;
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import java.util.ArrayList;
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/**
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* **15.17 (Geometry: find the bounding rectangle) Write a program that enables the user
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* to add and remove points in a two-dimensional plane dynamically, as shown
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* in Figure 15.29a. A minimum bounding rectangle is updated as the points are
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* added and removed. Assume that the radius of each point is 10 pixels
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*/
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public class Exercise15_17 extends javafx.application.Application {
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Pane pane = new Pane();
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ArrayList<Circle> points = new ArrayList<>();
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static final int RADIUS = 10;
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static final Color FILL_COLOR = Color.TRANSPARENT;
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static final Color LINE_COLOR = Color.BLACK;
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static final Label instructionsHeader = new Label("INSTRUCTION");
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static final Label addInstruction = new Label("Add: Left Click");
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static final Label removeInstruction = new Label("Remove: Right Click");
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public static void main(String[] args) {
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Application.launch(args);
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}
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@Override
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public void start(Stage primaryStage) {
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double width = 600;
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double height = 400;
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VBox instructionsBox = new VBox();
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instructionsBox.setPadding(new Insets(5, 5, 5, 5));
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instructionsBox.setStyle("-fx-border-color: black");
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instructionsBox.getChildren().addAll(instructionsHeader, addInstruction, removeInstruction);
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Pane infoPane = new Pane(instructionsBox);
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infoPane.setPadding(new Insets(10, 10, 10, 10));
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pane.getChildren().addAll(infoPane);
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instructionsBox.setLayoutX(10);
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instructionsBox.setLayoutY(10);
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pane.setOnMouseClicked(e -> {
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double x = e.getX();
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double y = e.getY();
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if (infoPane.contains(x, y)) return;
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if (e.getButton() == MouseButton.PRIMARY) {
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Circle c = drawPoint(x, y);
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points.add(c);
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pane.getChildren().add(c);
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drawMinBoundingRec();
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} else if (e.getButton() == MouseButton.SECONDARY) {
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removePoint(x, y);
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drawMinBoundingRec();
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}
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});
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Scene scene = new Scene(pane, width, height);
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primaryStage.setScene(scene);
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primaryStage.setTitle("click to draw circle");
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primaryStage.show();
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}
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private Circle drawPoint(double x, double y) {
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Circle c = new Circle(x, y, RADIUS, FILL_COLOR);
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c.setStroke(LINE_COLOR);
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return c;
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}
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private void drawMinBoundingRec() {
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clearCurrentRectangle();
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if (points.isEmpty()) return;
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Circle top = points.get(0);
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Circle bottom = points.get(0);
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Circle right = points.get(0);
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Circle left = points.get(0);
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for (Circle c : points) {
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if (c.getCenterX() < left.getCenterX()) left = c;
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if (c.getCenterX() > right.getCenterX()) right = c;
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if (c.getCenterY() > bottom.getCenterY()) bottom = c;
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if (c.getCenterY() < top.getCenterY()) top = c;
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}
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double width = right.getCenterX() - left.getCenterX() + top.getRadius() * 2;
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double height = bottom.getCenterY() - top.getCenterY() + top.getRadius() * 2;
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double centerX = (right.getCenterX() + left.getCenterX()) / 2;
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double centerY = (top.getCenterY() + bottom.getCenterY()) / 2;
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Rectangle rec = calculateRectangle(centerX, centerY, width, height);
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pane.getChildren().add(rec);
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}
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Rectangle calculateRectangle(double centerX, double centerY, double width, double height) {
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Rectangle rec = new Rectangle(centerX - width / 2, centerY - height / 2, width, height);
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rec.setStroke(LINE_COLOR);
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rec.setFill(FILL_COLOR);
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return rec;
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}
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private void removePoint(double x, double y) {
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ObservableList<Node> list = pane.getChildren();
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for (int i = list.size() - 1; i >= 0; i--) {
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Node c = list.get(i);
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if (c instanceof Circle && c.contains(x, y)) {
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pane.getChildren().remove(c);
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points.remove(c);
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break;
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}
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}
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}
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private void clearCurrentRectangle() {
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ObservableList<Node> list = pane.getChildren();
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for (Node c : list) {
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if (c instanceof Rectangle) {
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pane.getChildren().remove(c);
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break;
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}
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}
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}
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}

‎ch_15/Exercise15_18.java‎

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package ch_15;
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import javafx.application.Application;
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import javafx.scene.Scene;
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import javafx.scene.layout.Pane;
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import javafx.scene.paint.Color;
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import javafx.scene.shape.Rectangle;
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import javafx.stage.Stage;
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/**
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* **15.18 (Move a rectangle using mouse) Write a program that displays a rectangle.
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* You can point the mouse inside the rectangle and drag (i.e., move with mouse
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* pressed) the rectangle wherever the mouse goes. The mouse point becomes the
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* center of the rectangle.
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*/
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public class Exercise15_18 extends javafx.application.Application {
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static final double WIDTH = 600;
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static final double HEIGHT = 600;
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static final Color FILL_COLOR = Color.TRANSPARENT;
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static final Color STROKE_COLOR = Color.BLACK;
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public static void main(String[] args) {
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Application.launch(args);
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}
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@Override
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public void start(Stage primaryStage) {
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Rectangle rec = rectangle();
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Pane pane = new Pane(rec);
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rec.setOnMouseDragged(e -> {
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rec.setX(e.getX() - rec.getWidth() / 2);
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rec.setY(e.getY() - rec.getHeight() / 2);
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});
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primaryStage.setScene(new Scene(pane, WIDTH, HEIGHT));
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primaryStage.setTitle("Move a rectangle using mouse");
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primaryStage.show();
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}
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Rectangle rectangle() {
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Rectangle rec = new Rectangle(WIDTH / 2, HEIGHT / 2, 60, 30);
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rec.setFill(FILL_COLOR);
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rec.setStroke(STROKE_COLOR);
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return rec;
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}
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}

‎ch_15/Exercise15_19.java‎

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package ch_15;
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import ch_09.exercise09_06.StopWatch;
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import javafx.application.Application;
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import javafx.scene.Scene;
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import javafx.scene.layout.Pane;
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import javafx.scene.paint.Color;
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import javafx.scene.shape.Circle;
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import javafx.scene.text.Text;
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import javafx.stage.Stage;
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import java.util.concurrent.atomic.AtomicInteger;
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/**
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* **15.19 (Game: eye-hand coordination) Write a program that displays a circle of radius
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* 10 pixels filled with a random color at a random location on a pane, as shown
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* in Figure 15.29b. When you click the circle, it disappears and a new random color
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* circle is displayed at another random location. After twenty circles are
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* clicked, display the time spent in the pane, as shown in Figure 15.29c
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*/
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public class Exercise15_19 extends javafx.application.Application {
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private final double WIDTH = 600;
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private final double HEIGHT = 600;
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static final int MAX_CIRCLE_COUNT = 20;
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static final String TITLE_TEXT = "Exercise15_19";
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public static void main(String[] args) {
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Application.launch(args);
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}
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@Override
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public void start(Stage primaryStage) {
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AtomicInteger circleCount = new AtomicInteger();
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Circle circle = new Circle(0, 0, 10);
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drawCircle(circle);
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Pane pane = new Pane(circle);
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Text countText = new Text(50, 50, String.valueOf(circleCount));
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pane.getChildren().add(countText);
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StopWatch stopWatch = new StopWatch();
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circle.setOnMouseClicked(e -> {
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int currentCount = circleCount.get();
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if (currentCount == 0) {
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stopWatch.start();
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} else if (currentCount < MAX_CIRCLE_COUNT - 1) {
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circleCount.getAndIncrement();
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countText.setText(String.valueOf(circleCount));
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drawCircle(circle);
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} else {
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stopWatch.stop();
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circleCount.getAndIncrement();
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countText.setText(String.valueOf(circleCount));
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pane.getChildren().remove(circle);
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pane.getChildren().add(new Text(WIDTH / 2, HEIGHT / 2, "Time spent is " +
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stopWatch.getElapsedTime() + " milliseconds"));
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}
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});
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primaryStage.setScene(new Scene(pane, WIDTH, HEIGHT));
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primaryStage.setTitle(TITLE_TEXT);
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primaryStage.show();
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}
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private void drawCircle(Circle circle) {
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double min = circle.getRadius() + 5;
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double max = WIDTH - circle.getRadius() - 5;
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circle.setCenterX((Math.random() * (max - min) + min));
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max = WIDTH - circle.getRadius() - 5;
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circle.setCenterY((Math.random() * (max - min) + min));
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circle.setFill(new Color(Math.random(), Math.random(), Math.random(), 1));
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}
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}

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