Question

Modify the AlienDirection program from this chapter so that the image is not allowed to move out of the visible area of the window. Ignore any key that would allow this to happen.

*Ask if you have any questions about the assignment I will try to clarify

Textbook - JAVA FOUNDATIONS: INTRODUCTION TO PROGRAM DESIGN AND DATA STRUCTURES 5TH EDITION

Starter Code Provided :

import javafx.application.Application;

import javafx.scene.Group;

import javafx.scene.Scene;

import javafx.scene.image.Image;

import javafx.scene.image.ImageView;

import javafx.scene.input.KeyEvent;

import javafx.scene.paint.Color;

import javafx.stage.Stage;

public class AlienDirection extends Application
{
public final static int JUMP = 10;
  
private ImageView imageView;

//--------------------------------------------------------------------
// Displays an image that can be moved using the arrow keys.
//--------------------------------------------------------------------
public void start(Stage primaryStage)
{
Image alien = new Image("alien.png");
  
imageView = new ImageView(alien);
imageView.setX(20);
imageView.setY(20);
  
Group root = new Group(imageView);

Scene scene = new Scene(root, 400, 200, Color.BLACK);
scene.setOnKeyPressed(this::processKeyPress);

primaryStage.setTitle("Alien Direction");
primaryStage.setScene(scene);
primaryStage.show();
}
  
//--------------------------------------------------------------------
// Modifies the position of the image view when an arrow key is
// pressed.
//--------------------------------------------------------------------
public void processKeyPress(KeyEvent event)
{
switch (event.getCode())
{
case UP:
imageView.setY(imageView.getY() - JUMP);
break;
case DOWN:
imageView.setY(imageView.getY() + JUMP);
break;
case RIGHT:
imageView.setX(imageView.getX() + JUMP);
break;
case LEFT:
imageView.setX(imageView.getX() - JUMP);
break;
default:
break; // do nothing if it's not an arrow key
}
}
  
public static void main(String[] args)
{
launch(args);
}
}

Answer 1

Just comment or remove code from processKeyPress method so that image will not move


import javafx.application.Application;

import javafx.scene.Group;

import javafx.scene.Scene;

import javafx.scene.image.Image;

import javafx.scene.image.ImageView;

import javafx.scene.input.KeyEvent;

import javafx.scene.paint.Color;

import javafx.stage.Stage;

public class AlienDirection extends Application
{
    public final static int JUMP = 10;

    private ImageView imageView;

    //--------------------------------------------------------------------
// Displays an image that can be moved using the arrow keys.
//--------------------------------------------------------------------
    public void start(Stage primaryStage)
    {
        Image alien = new Image("alien.png");

        imageView = new ImageView(alien);
        imageView.setX(20);
        imageView.setY(20);

        Group root = new Group(imageView);

        Scene scene = new Scene(root, 400, 200, Color.BLACK);
        scene.setOnKeyPressed(this::processKeyPress);

        primaryStage.setTitle("Alien Direction");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    //--------------------------------------------------------------------
// Modifies the position of the image view when an arrow key is
// pressed.
//--------------------------------------------------------------------
    public void processKeyPress(KeyEvent event)
    {
        switch (event.getCode())
        {   
            case UP:
                
                break;
            case DOWN:
                break;
            case RIGHT:
                
                break;
            case LEFT:
                break;
            default:
                break; // do nothing if it's not an arrow key
        }
    }

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