如何将地图地图列表合并到地图中？

Question

你能帮帮我Java Streams吗？

正如你从标题中看到的,我需要合并List<Map<String, Map<String, Genuineness>>>到Map<String, Map<String, Genuineness>>.

该列表表示为List<Map<String, Map<String, Genuineness>>>:

[  
   {  
      "USER_1":{  
         "APP_1":{  
            "total":1,
            "totalGenuine":1,
            "totalDevelopment":1
         }
      },
      "USER_2":{  
         "APP_1":{  
            "total":1,
            "totalGenuine":1,
            "totalDevelopment":1
         },
         "APP_2":{  
            "total":2,
            "totalGenuine":2,
            "totalDevelopment":2
         }
      }
   },
   {  
      "USER_1":{  
         "APP_1":{  
            "total":1,
            "totalGenuine":1,
            "totalDevelopment":1
         }
      },
      "USER_2":{  
         "APP_1":{  
            "total":1,
            "totalGenuine":1,
            "totalDevelopment":1
         },
         "APP_2":{  
            "total":2,
            "totalGenuine":2,
            "totalDevelopment":2
         }
      }
   }
]

因此,正如您所看到的,重复的键可能无处不在.我的目标是Map<String, Map<String, Genuineness>>通过合并将它们组合在一起Genuineness.合并Genuineness只是意味着返回一个新的对象与总结了值total,totalGenuine和totalDevelopment.

这是我的实现失败:

final Map<String, Map<String, Genuineness>> map = taskHandles.stream().map(this::mapTaskHandle)
                .flatMap(m -> m.entrySet().stream()).collect(
                        Collectors.toMap(Map.Entry::getKey, e -> e.getValue().entrySet().stream()
                                .collect(
                                        Collectors.toMap(Map.Entry::getKey,
                                                g -> new Genuineness(g.getValue().getTotal(), g.getValue().getTotalGenuine(), g.getValue().getTotalDevelopment()),
                                                (g1, g2) -> new Genuineness(g1.getTotal() + g2.getTotal(),
                                                        g1.getTotalGenuine() + g2.getTotalGenuine(),
                                                        g1.getTotalDevelopment() + g2.getTotalGenuine()
                                                )
                                        )
                                )
                        )
                );

它失败并带有消息:

java.lang.IllegalStateException: Duplicate key {TEST_33_33_APP_1=live.attach.billing.domain.model.billing.Genuineness@951b6fe}

所以,似乎在我的实现中我已经指出了如何组合内部地图但没有合并外部地图的值,我不知道该怎么做.

我非常感谢你的帮助.先感谢您!

更新:预期输出:

   {  
      "USER_1":{  
         "APP_1":{  
            "total":2,
            "totalGenuine":2,
            "totalDevelopment":2
         }
      },
      "USER_2":{  
         "APP_1":{  
            "total":2,
            "totalGenuine":2,
            "totalDevelopment":2
         },
         "APP_2":{  
            "total":4,
            "totalGenuine":4,
            "totalDevelopment":4
         }
      }
   }

Answer 1

老实说，这是一个可怕的数据结构，代码的维护者将很难发现出现的问题。

您应该退后一步并考虑重构代码，任何可以通过在最外面使用以下合并函数来解决缺失部分的方法toMap：

(l, r) -> {
      r.forEach((k, v) -> l.merge(k, v,
                    (bi, bii) -> new Genuineness(bi.getTotal() + bii.getTotal(),
                               bi.getTotalGenuine() + bii.getTotalGenuine(),
                               bi.getTotalDevelopment() + bii.getTotalGenuine())));
       return l;
}

完整代码：

taskHandles.stream().map(this::mapTaskHandle)
                .flatMap(m -> m.entrySet().stream()).collect(
                        Collectors.toMap(Map.Entry::getKey, e -> e.getValue().entrySet().stream()
                                .collect(
                                        Collectors.toMap(Map.Entry::getKey,
                                                g -> new Genuineness(g.getValue().getTotal(), g.getValue().getTotalGenuine(), g.getValue().getTotalDevelopment()),
                                                (g1, g2) -> new Genuineness(g1.getTotal() + g2.getTotal(),
                                                        g1.getTotalGenuine() + g2.getTotalGenuine(),
                                                        g1.getTotalDevelopment() + g2.getTotalGenuine()
                                                )
                                        )
                                ),(l, r) -> {
                                  r.forEach((k, v) -> l.merge(k, v,
                                          (bi, bii) -> new Genuineness(bi.getTotal() + bii.getTotal(),
                                                  bi.getTotalGenuine() + bii.getTotalGenuine(),
                                                  bi.getTotalDevelopment() + bii.getTotalGenuine())));
                                  return l;
                                }

                        )
                );

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