Android : Find Angle, and draw Bitmap at that angle?

Question

I am porting a game I have made, from Windows (Visual Studio c# XNA4) to Android.

In the game, I need to find the location of the users "touch" (Which I have done), and then "point" the player to this touch location (draw the player bitmap at this angle).

In c# and XNA4, I used the following:

Matrix rotationMatrix = Matrix.CreateRotationZ(playerAngle);
PlayerDirection = Vector2.Transform(up, rotationMatrix); 

If the players position was

x = 200;
y = 200; 

And the touch co-ordinates were

x = 300;
y = 300;

How would I make the player "point" at where the user touched?

Answer 1

In Java (I assume you are using Java for Android) you would do the following to find the angle:

private double getAngle(double x1, double y1, double x2, double y2)
{
    return Math.atan2(y2-y1, x2-x1);
}