List<Student> list = studentService.findBySpecialty(model.getSpecialty().getSpid());
for(Student student : list){
	Set<Replygroup> set = student.getReplygroups();
	if(set.size() != 0){
		boolean flag = true;
		Iterator<Replygroup> iterator = set.iterator();
		while(iterator.hasNext()){
			if(groupType.equals(iterator.next().getRgType())){
				flag = false;
				//當在這兒刪掉資料，然後到for那兒會直接跳出
				list.remove(student);
				break;
			}
		}
	}
}
 

修改如下

List<Student> list = studentService.findBySpecialty(model.getSpecialty().getSpid());
List<Student> listRemove = new ArrayList<Student>();
for(Student student : list){
	Set<Replygroup> set = student.getReplygroups();
	if(set.size() != 0){
		Iterator<Replygroup> iterator = set.iterator();
		while(iterator.hasNext()){
			if(groupType.equals(iterator.next().getRgType())){
				listRemove.add(student);
				break;
			}
		}
	}
}
list.removeAll(listRemove);