Review

SubLine.intersection() may return null.

Check result for null before using.

• missing/condition/null_check

org/apache/commons/math3/geometry/euclidean/twod/SubLine.java

intersection(SubLine, boolean)

class SubLine {
    /** Get the intersection of the instance and another sub-line.
     * <p>
     * This method is related to the {@link Line#intersection(Line)
     * intersection} method in the {@link Line Line} class, but in addition
     * to compute the point along infinite lines, it also checks the point
     * lies on both sub-line ranges.
     * </p>
     * @param subLine other sub-line which may intersect instance
     * @param includeEndPoints if true, endpoints are considered to belong to
     * instance (i.e. they are closed sets) and may be returned, otherwise endpoints
     * are considered to not belong to instance (i.e. they are open sets) and intersection
     * occurring on endpoints lead to null being returned
     * @return the intersection point if there is one, null if the sub-lines don't intersect
     */
    public Vector2D intersection(final SubLine subLine, final boolean includeEndPoints) {

        // retrieve the underlying lines
        Line line1 = (Line) getHyperplane();
        Line line2 = (Line) subLine.getHyperplane();

        // compute the intersection on infinite line
        Vector2D v2D = line1.intersection(line2);

        // check location of point with respect to first sub-line
        Location loc1 = getRemainingRegion().checkPoint(line1.toSubSpace(v2D));

        // check location of point with respect to second sub-line
        Location loc2 = subLine.getRemainingRegion().checkPoint(line2.toSubSpace(v2D));

        if (includeEndPoints) {
            return ((loc1 != Location.OUTSIDE) && (loc2 != Location.OUTSIDE)) ? v2D : null;
        } else {
            return ((loc1 == Location.INSIDE) && (loc2 == Location.INSIDE)) ? v2D : null;
        }

    }

}

class CheckV2DNull {
  void pattern(Line line, Line other) {
    Vector2D v2D = line.intersection(other);
    if (v2D != null) {
      line.toSubSpace(v2D);
      other.toSubSpace(v2D);
    }
  }
}