如何在列表中获取最小值和最大值<map<> &gt; 对象

Question

嗨，我有以下列表> 我需要根据通道类型找到最小值和最大值，例如：485_0x07="Energy",485_0x08="Energy",485_0x06="Energy" 基于 Energy 键值

数据输入格式如下：

[{updatedTime=2017-10-24 23:00:55, 
  playload={"485_0x07":{"Energy":"1750.0","Voltage":"244.83","Current":"0.095795"},
            "485_0x06":{"Energy":"5761.0","Voltage":"244.31","Current":"10.1815"},
            "485_0x08":{"Energy":"2814.0","Voltage":"245.04","Current":"0.469673"},
            "485_0x01":{"Energy":"0.0","Voltage":"0.0","Current":"0.0"}}}, 
 {updatedTime=2017-10-24 23:01:05,
  playload={"485_0x07":{"Energy":"1750.0","Voltage":"244.83","Current":"0.095795"},
            "485_0x06":{"Energy":"5761.0","Voltage":"244.31","Current":"10.1815"},
            "485_0x08":{"Energy":"2814.0","Voltage":"245.04","Current":"0.469673"},
            "485_0x01":{"Energy":"0.0","Voltage":"0.0","Current":"0.0"}}}, 
 {updatedTime=2017-10-24 23:59:49,
  playload={"485_0x07":{"Energy":"1754.0","Voltage":"238.99","Current":"0.100577"},
            "485_0x06":{"Energy":"5762.0","Voltage":"238.04","Current":"10.1387"},
            "485_0x08":{"Energy":"2814.0","Voltage":"238.84","Current":"0.43637"},
            "485_0x01":{"Energy":"0.0","Voltage":"0.0","Current":"0.0"}}}] 

谢谢

Answer 1

如果没有任何提供的类，我只会假设您输入中的每个元素都有一个类。 您可以尝试使用这样的流：

input.stream()
     .flatMap(hbaseObject -> hbaseObject.getPayload().getChannels().stream())
     .collect(Collectors.groupingBy(channel -> channel.getKey(), 
                                    Collectors.summarizingDouble(channel -> channel.getEnergy()))

这会给你一个Map<ChannelKey, DoubleSummaryStatistics> 。 统计对象包含最小值、最大值和平均值。