list排序

/*** 目标：有照片的放前边，没有照片的放后边**/1、UserVO.javaprivate String userName;//用户名private int order;//排序值private String photo;//照片。。。省略set/get方法2、SortUtils.javapublic void sortList(List<UserVO> list){        Collections.sort(list,new Comparator<UserVO>(){            public int compare(UserVO vo1, UserVO vo2)            {                return vo1.getPhoto() != null? 0 : 1;            }        });    }//或者    Collections.sort(list,new Comparator<UserVO>(){                                public int compare(UserVO arg0, UserVO arg1) {       //            第一次比较专业                      int i = arg0.getOrder().compareTo(arg1.getOrder());       //                  如果专业相同则进行第二次比较                  if(i==0){//                      第二次比较                      int j=arg0.getXXX().compareTo(arg1.getXXX());//                      如果学制相同则返回按年龄排序                      if(j==0){                          return arg0.getCCC().compareTo(arg1.getCCC());                      }                      return j;                  }                  return i;                  }              });