private double findAngle(Point originPoint,Point targetPoint){
  int x1=originPoint.x;
  int y1=originPoint.y;
  int x2=targetPoint.x;
  int y2=targetPoint.y;
  double angle=0.0;
  double offset=0.0;
  double sideA=x2 - x1;
  double sideB=0.0;
  if (y1 >= y2) {
    sideB=y1 - y2;
    offset=Math.toRadians(-90);
  }
 else {
    sideB=-(y2 - y1);
    offset=Math.toRadians(90);
  }
  if (sideB == 0) {
    return angle;
  }
  angle=Math.atan(sideA / sideB);
  return angle + offset;
}

private double findAngle ( Point originPoint , Point targetPoint ) { int x1 = originPoint . x ; int y1 = originPoint . y ; int x2 = targetPoint . x ; int y2 = targetPoint . y ; double angle = 0.0 ; double offset = 0.0 ; double sideA = x2 - x1 ; double sideB = 0.0 ; if ( y1 >= y2 ) { sideB = y1 - y2 ; offset = Math . toRadians ( - 90 ) ; } else { sideB = - ( y2 - y1 ) ; offset = Math . toRadians ( 90 ) ; } if ( sideB == 0 ) { return angle ; } angle = Math . atan ( sideA / sideB ) ; return angle + offset ; }
uses trig to find angle of the arrow
