Write a program that moves the ball in a pane. You should define a pane class for displaying the ball and provide the methods for moving the ball left, right, up. and down, as shown in Figure Check the boundary to prevent the ball from moving out of sight completely. Exercise uses the buttons to move the ball. Solution public class Exe extends Application { public void start(Stage primaryStage) throws Exception { double width = 400; double height = 400; BallPane ballPane = new BallPane(width / 2,height / 2, Math.min(width,height) / 15); Button btUp = new Button(\"Up\"); btUp.setOnAction(e -> ballPane.moveUp()); Button btDown = new Button(\"Down\"); btDown.setOnAction(e -> ballPane.moveDown()); Button btLeft = new Button(\"Left\"); btLeft.setOnAction(e -> ballPane.moveLeft()); Button btRight = new Button(\"Right\"); btRight.setOnAction(e -> ballPane.moveRight()); HBox buttons = new HBox(btUp, btDown, btLeft, btRight); buttons.setAlignment(Pos.BOTTOM_CENTER); buttons.setSpacing(10); buttons.setPadding(new Insets(10, 10, 10, 10)); BorderPane pane = new BorderPane(); pane.setCenter(ballPane); pane.setBottom(buttons); Scene scene = new Scene(pane, width, height); primaryStage.setScene(scene); primaryStage.setTitle(\"Click to move ball\"); primaryStage.show(); } private class BallPane extends Pane { private Circle mCircle; public BallPane() { this(0, 0, 10); } public BallPane(double centerX, double centerY, double radius) { mCircle = new Circle(centerX, centerY, radius); getChildren().add(mCircle); } public void moveUp() { if (mCircle.getCenterY() - mCircle.getRadius() - 10 < 0) return; mCircle.setCenterY(mCircle.getCenterY() - 10); } public void moveDown() { if (mCircle.getCenterY() + mCircle.getRadius() + 10 > getHeight()) return; mCircle.setCenterY(mCircle.getCenterY() + 10); } public void moveRight() { if (mCircle.getCenterX() + mCircle.getRadius() + 10 > getWidth()) return; mCircle.setCenterX(mCircle.getCenterX() + 10); } public void moveLeft() { if (mCircle.getCenterX() - mCircle.getRadius() - 10 < 0) return; mCircle.setCenterX(mCircle.getCenterX() - 10); } } public static void main(String[] args) { Application.launch(args); } }.

1. Write a program that moves the ball in a pane. You should define a pane class for displaying the
ball and provide the methods for moving the ball left, right, up. and down, as shown in Figure
Check the boundary to prevent the ball from moving out of sight completely. Exercise uses the
buttons to move the ball.
Solution
public class Exe extends Application
{
public void start(Stage primaryStage) throws Exception
{
double width = 400;
double height = 400;
BallPane ballPane = new BallPane(width / 2,height / 2, Math.min(width,height) / 15);
Button btUp = new Button("Up");
btUp.setOnAction(e -> ballPane.moveUp());
Button btDown = new Button("Down");
btDown.setOnAction(e -> ballPane.moveDown());
Button btLeft = new Button("Left");
btLeft.setOnAction(e -> ballPane.moveLeft());
Button btRight = new Button("Right");
btRight.setOnAction(e -> ballPane.moveRight());
HBox buttons = new HBox(btUp, btDown, btLeft, btRight);
buttons.setAlignment(Pos.BOTTOM_CENTER);
buttons.setSpacing(10);
buttons.setPadding(new Insets(10, 10, 10, 10));
BorderPane pane = new BorderPane();
pane.setCenter(ballPane);
pane.setBottom(buttons);
Scene scene = new Scene(pane, width, height);
primaryStage.setScene(scene);
primaryStage.setTitle("Click to move ball");
primaryStage.show();
}
private class BallPane extends Pane
{

2. private Circle mCircle;
public BallPane()
{
this(0, 0, 10);
}
public BallPane(double centerX, double centerY, double radius)
{
mCircle = new Circle(centerX, centerY, radius);
getChildren().add(mCircle);
}
public void moveUp()
{
if (mCircle.getCenterY() - mCircle.getRadius() - 10 < 0) return;
mCircle.setCenterY(mCircle.getCenterY() - 10);
}
public void moveDown()
{
if (mCircle.getCenterY() + mCircle.getRadius() + 10 > getHeight()) return;
mCircle.setCenterY(mCircle.getCenterY() + 10);
}
public void moveRight()
{
if (mCircle.getCenterX() + mCircle.getRadius() + 10 > getWidth()) return;
mCircle.setCenterX(mCircle.getCenterX() + 10);
}
public void moveLeft()
{
if (mCircle.getCenterX() - mCircle.getRadius() - 10 < 0) return;
mCircle.setCenterX(mCircle.getCenterX() - 10);
}
}
public static void main(String[] args)
{
Application.launch(args);
}
}