CODEWITHSUNDEEP
java
Michał Tabor
Michał Tabor

Reputation: 2467

Private fields from abstract class cannot be accessed in the subclass

I have class which represents every object in my simple game (player, enemy, beam etc - they all have many commons like speed, position, dmg). So i made class named Thing. Here is how it looks like:

public abstract class Thing {
    private Image image;
    private float x;
    private float y;
    private float speed;
    private final int WIDTH;
    private final int HEIGHT;

    public Thing(String filename, float x, float y, float speed) {
        try {
            Image image = ImageIO.read(new File(filename));
        } catch (Exception e) {}
        this.x = x;
        this.y = y;
        this.speed = speed;
        WIDTH = image.getWidth(null);
        HEIGHT = image.getHeight(null);
    }

    //Zwraca ksztalt do sprawdzania czy contains...
    public Rectangle2D getShade() {
        return new Rectangle2D.Float(x, y, WIDTH, HEIGHT);
    }

    public Image getImage() {
        return image;
    }

    public Point2D getPoint() {
        return new Point2D.Float(x, y);
    }

    public float getX() {
        return x;
    }

    public float getY() {
        return y;
    }
}

I have extended the class Player:

public class Player extends Thing {
    public Player(String filename, float x, float y, float speed) {
        super(filename, x, y, speed);
    }

    public void moveToPoint(Point2D targetPoint) {
        int targetX = (int)targetPoint.getX();
        int targetY = (int)targetPoint.getY();
        if ( ((int)x+20 < targetX+3) && ((int)x+20 > targetX-3) ) {
            return;
        }
        float distanceX = targetX - x;
        float distanceY = targetY - y;
        //Dodanie 20px wymiarow statku
        distanceX -= 20;
        distanceY -= 20;
        //Ustalenie wartosci shiftow
        float shiftX = speed;
        float shiftY = speed;
        if (abs(distanceX) > abs(distanceY)) {
            shiftY = abs(distanceY) / abs(distanceX) * speed;
        }
        if (abs(distanceY) > abs(distanceX)) {
            shiftX = abs(distanceX) / abs(distanceY) * speed;
        }
        //Zmiana kierunku shifta w zaleznosci od polozenia
        if (distanceX < 0) {
            shiftX = -shiftX;
        }
        if (distanceY < 0) {
            shiftY = -shiftY;
        }
        //Jezeli statek mialby wyjsc poza granice to przerywamy
        if ( (((int)x+shiftX < 0) || ((int)x+shiftX > 260)) || ((y+shiftY < 0) || (y+shiftY > 360)) ) {
            return;
        }
        //Zmiana pozycji gracza
        x += shiftX;
        y += shiftY;
    }
}

And here is the problem because my IDE underlines x, y and speed fields red and tells they cannot be accessed from Player class. I tried to change them into private and default but there appears an error after that. What am I doing wrong? When i create new object from class which extends Thing I want to copy all fields and init them as it is said in constructor. So how to repair it?

Upvotes: 4

Views: 28762

Answers (2)

kosa
kosa

Reputation: 66637

You need to use getX(), getY() etc., because x,y, speed are private variables for class Thing.

The fact that Player extends Thing doesn't mean Player can access private fields. Thing provided public get... set... to access its private variables.

Upvotes: 6

Mike
Mike

Reputation: 2434

Change the variables x, y, and speed to protected, or use the accessors getX(), getY(), getSpeed() (getSpeed() needs to be added in this case) to solve the access issues.

The error that appeared after you changed them to default was the fact that you're calling abs(...) instead of Math.abs(...). Change all instances of abs(...) to Math.abs(...) to get rid of the new errors.

Upvotes: 0

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