Code to calculate angle not working

Question

I am trying to calculate the angle in degrees between tow points in java. This is the code i am using to calculate the angle.

public static double calcAngle(Point.Double p1, Point.Double p2)
{
    double xDiff = p2.x - p1.x;
    double yDiff = p2.y - p1.y;
    return Math.toDegrees(Math.atan2(yDiff, xDiff));
}

Here is the rest of my code

double playerX = panel.getCharacter().getX();
double playerY = panel.getCharacter().getY();
int dispenserX = x*Block.WIDTH;
int dispenserY = y*Block.HEIGHT;
Point2D.Double player = new Point2D.Double(playerX, playerY);
Point2D.Double dispenser = new Point2D.Double(dispenserX, dispenserY);
double angle = calcAngle(dispenser, player);
System.out.println(angle);
panel.addEntity(newEntityFireball(x*Block.WIDTH,y*Block.HEIGHT,angle,1));//adds a fireball at a 45 degree angle
System.out.println(angle);
System.out.println(dispenser);
System.out.println(player);

The fireball fired from the dispenser is not aimed at the player why? And it seems to move at a random angle.

Edit here is the fireball class

import java.awt.image.BufferedImage;
import java.io.IOException;

import javax.imageio.ImageIO;

public class EntityFireball extends Entity 
{
    private double angle;
    private double speed;
    private int life;

    public EntityFireball(double x, double y, double angle, double speed) 
    {
        super(x, y, 20, 20);
        this.angle = angle;
        this.speed = speed;
    }

    public void update(boolean inRange)
    {
        life++;

        if(life>2500)
            removeEntityFromGame(this);

        if(inRange)
        {
            float xDirection = (float) (Math.sin((float) Math.toRadians(angle)) * speed);
            float yDirection = (float) (Math.cos((float) Math.toRadians(angle)) * -speed);
            double newX = getX() + xDirection;
            double newY = getY() + yDirection;
            setX(newX);
            setY(newY);
        }
    }

    public BufferedImage getImage() 
    {
        try
        {
            return ImageIO.read(Main.class.getResourceAsStream("/images/Fireball.png"));
        } 
        catch (IOException e)
        {
            return null;
        }
    }
    }

Answer 1

change

float xDirection = (float) (Math.sin((float) Math.toRadians(angle)) * speed);
float yDirection = (float) (Math.cos((float) Math.toRadians(angle)) * -speed);

to

float xDirection = (float) (Math.cos((float) Math.toRadians(angle)) * speed);
float yDirection = (float) (Math.sin((float) Math.toRadians(angle)) * speed);

Also, you are changing the 2D course vector into an angle, and then changing it back to a 2D course vector. It's a decent amount of circular trig that lands you the same answer that you initially started with. Is there a reason you don't just leave it a vector?

public static Point2D.Double calcAngle(Point.Double p1, Point.Double p2){
    double xDiff = p2.x - p1.x;
    double yDiff = p2.y - p1.y;
    return new Point2D.Double(xDiff,yDiff);
}


public class EntityFireball extends Entity {
    private Point2D.Double course;
    private double speed;
    private int life;

    public EntityFireball(double x, double y, double angle, Point2D.Double course){
        super(x, y, 20, 20);
        this.angle = angle;
        this.course=course;
    }

    public void update(boolean inRange){
        life++;
        if(life>2500)
            removeEntityFromGame(this);

        if(inRange){
            float xDirection = course.x;
            float yDirection = course.y;
            double newX = getX() + xDirection;
            double newY = getY() + yDirection;
            setX(newX);
            setY(newY);
        }
    }
}

Answer 2

My guess is that you've converted the angle to degrees but are treating it later as a radian angle when you do your drawing. That would explain why it's in "random directions"

Answer 3

Just take the absolute values:

public static double calcAngle(Point.Double p1, Point.Double p2)
{
    double xDiff = Math.abs(p2.x - p1.x);
    double yDiff = Math.abs(p2.y - p1.y);
    return Math.toDegrees(Math.atan2(yDiff, xDiff));
}