Java：Collection.shuffle内存使用情况？

Question

我正在使用Arraylist（Classroom是我的代码中的一个类），我在其中存储大量数据（很多课堂）。我在循环中使用这个Arraylist来提取单个教室并在其上运行算法。我的代码在循环开始时随机播放Arraylist集合，选择Arraylist中第0个位置的教室。我正在使用Collection.shuffle（）函数进行shuffle。我的问题是我的代码在堆空间不足并且在运行期间停止。

代码片段如下所示

ArrayList<ClassroomName> names = new ArrayList<ClassroomName>(Arrays.asList(ClassroomName.values()));
for(int x=0;x<names.size();x++){
        Collections.shuffle(names);
        ClassroomName name = names.remove(0);
        int classID = getClassID(name, location);
        if(classID != -1){
            c = new Classroom(classID);
            if(c!=null){
                //System.out.println("Call findEmptySlotsForClassroom for just checking. Not retreiving");
                /*
                 * Check the capacity of the classroom and the required capacity
                 */
                DBAnnotation.annoate("classCap", "classroom", "ClassroomCapacity", true);
                int classCap = c.getClassroomCapacity();
                if(classCap >= expectedCapacity){
                    /*
                     * Find empty timeslot for the classroom
                     */
                    times = c.findOpenSlotsForClassroom(timeSlotType);
                    /*
                     * If atleast one empty slot is found, return the classroom in which it was found
                     */
                    if(times.size()>0){
                        DBAnnotation.annoate("loc", "classroom", "ClassroomLocation", true);
                        ClassroomLocation loc = c.getClassroomLocation();

                        DBAnnotation.annoate("cName", "classroom", "ClassroomName", true);
                        ClassroomName cName = c.getClassroomName();

                        System.out.println("Found a classroom with empty time slots:"+cName.toString()+" "
                                + ""+ loc.toString());
                        break;
                    }
                }
                c = null;
            }
        }
    }

我认为shuffle会导致大量内存使用。我不确定是什么导致内存溢出。如果有人可以提供帮助，请告诉我。如果需要，我愿意提供任何其他缺失的信息。

感谢。