Java8进行多个字段分组统计实现

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// 分组统计 Map<String, Long> countMap = records.stream().collect(Collectors.groupingBy(o -> o.getProductType() + "_" + o.getCountry(), Collectors.counting()));   List<Record> countRecords = countMap.keySet().stream().map(key -> {     String[] temp = key.split("_");     String productType = temp[0];     String country = temp[1];           Record record = new Record();     record.set("device_type", productType);     record.set("location", country;     record.set("count", countMap.get(key).intValue());     return record; }).collect(Collectors.toList());

　　

作者：尤灯塔

出处：https://www.cnblogs.com/30go/