code: public static double getAngle(double xDiff, double yDiff) {
          double angle = 0;
          //		logger.debug("getAngle->xDiff: " + xDiff);
          //		logger.debug("getAngle->yDiff: " + yDiff);
          if (xDiff >= 0 && yDiff >= 0) {
              angle = Math.atan(yDiff / xDiff);
          } else if (xDiff < 0 && yDiff >= 0) {
              angle = Math.PI + Math.atan(yDiff / xDiff);
          } else if (xDiff < 0 && yDiff < 0) {
              angle = Math.PI + Math.atan(yDiff / xDiff);
          } else if (xDiff >= 0 && yDiff < 0) {
              angle = 2 * Math.PI + Math.atan(yDiff / xDiff);
          }
          return angle;
      }
docs: Gets the angle attribute of the GeometryTools class.
  
  @param  xDiff  Description of the Parameter
  @param  yDiff  Description of the Parameter
  @return        The angle value