java list對象 排序

Collections.sort(eventList);
Collections.sort(dataList,
new Comparator<InverterVO>() {
									@Override
									public int compare(InverterVO obj1,
											InverterVO obj2) {
										Double do1 = Utils.formatDouble(obj1
												.getAcPowerRate());
										Double do2 = Utils.formatDouble(obj2
												.getAcPowerRate());
										if ("1".equals(sortType)) { // 升序
											return (int) (do1.compareTo(do2));
										} else {
											return (int) (do2.compareTo(do1));
										}
									}
								});