遍历list，把id相同的某字段拼接

  1. publicstaticvoidmain(String[] args) {
  2.     Listlist=newArrayList<>();
  3.     BindImageCodeDTObindImageCodeDTO=newBindImageCodeDTO();
  4.     bindImageCodeDTO.setExpressCode("test111");
  5.     bindImageCodeDTO.setSecurityDataId(1111111L);
  7.     BindImageCodeDTObindImageCodeDTO3=newBindImageCodeDTO();
  8.     bindImageCodeDTO3.setExpressCode("test333");
  9.     bindImageCodeDTO3.setSecurityDataId(222222L);
  11.     BindImageCodeDTObindImageCodeDTO4=newBindImageCodeDTO();
  12.     bindImageCodeDTO4.setExpressCode("test222");
  13.     bindImageCodeDTO4.setSecurityDataId(333333L);
  15.     BindImageCodeDTObindImageCodeDTO2=newBindImageCodeDTO();
  16.     bindImageCodeDTO2.setExpressCode("test222");
  17.     bindImageCodeDTO2.setSecurityDataId(1111111L);
  19.     list.add(bindImageCodeDTO);
  20.     list.add(bindImageCodeDTO3);
  21.     list.add(bindImageCodeDTO4);
  22.     list.add(bindImageCodeDTO2);
  24.     Map<Long,String>result=newHashMap<>();
  26.     for (BindImageCodeDTOimageCodeDTO : list) {
  27.         if (result.containsKey(imageCodeDTO.getSecurityDataId())){
  28.             result.put(imageCodeDTO.getSecurityDataId(),result.get(imageCodeDTO.getSecurityDataId())+","+imageCodeDTO.getExpressCode());
  29.         }else {
  30.             result.put(imageCodeDTO.getSecurityDataId(),imageCodeDTO.getExpressCode());
  31.         }
  32.     }
  34.     for (LongaLong : result.keySet()) {
  35.         System.out.println(aLong+"->"+result.get(aLong));
  36.     }
  38. }