private boolean doClashesOccur(String id) { // we want to take this course Course course = getCourse(id); boolean ok = true; List<Course> taking = getCoursesTakingFull(); for (Course course_ : taking) { // different semester if (course.isFirstSemester() && course_.isSecondSemester()) continue; // check for events clashes for (Event event1 : course.getEvents()) { for (Event event2 : course_.getEvents()) { if (event1.getStartInt() == event2.getStartInt()) { ok = false; } } } } return ok; }