JAVA合并两个具有相同key的map为list,不多说，直接上代码：
代码语言：javascript复制public class MapUtil {
public static void main(String[] args){
List<Map<String,String>> osvList = new ArrayList<>();
Map<String,String> map1 = new HashMap<>();
map1.put("osV","5.1");
map1.put("gaidNum","100");
Map<String,String> map2 = new HashMap<>();
map2.put("osV","4.4.2");
map2.put("gaidNum","150");
osvList.add(map1);
osvList.add(map2);
List<Map<String,String>> ipList = new ArrayList<>();
Map<String,String> map3 = new HashMap<>();
map3.put("osV","5.1");
map3.put("ipNum","200");
Map<String,String> map4 = new HashMap<>();
map4.put("osV","4.4.2");
map4.put("ipNum","300");
ipList.add(map3);
ipList.add(map4);
List<Map<String,String>> mapsList = new ArrayList<>();
mapsList.add(map1);
mapsList.add(map3);
System.out.println("mapsList=" mapsList);
List<Map<String,String>> megeList = merge(mapsList,"osV");
System.out.println("megeList=" megeList);
}
/**
* 合并两个具有相同key的map为list
* @param m1 要合并的list
* @param mergeKey 以哪个key为基准合并
* @return
*/
public static List<Map<String, String>> merge(List<Map<String, String>> m1, String mergeKey){
Set<String> set = new HashSet<>();
return m1.stream()
.filter(map->map.get(mergeKey)!=null)
.collect(Collectors.groupingBy(o->{
set.addAll(o.keySet());//暂存所有key
return o.get(mergeKey).toString(); //按mergeKey分组
}))
.entrySet().stream().map(o->{
Map<String, String> map = o.getValue().stream().flatMap(m->{ //合并
return m.entrySet().stream();
}).collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (a,b)->b));
set.stream().forEach(k->{//为没有的key赋值0
if(!map.containsKey(k)) map.put(k, "0");
});
return map;
}).collect(Collectors.toList());
}
}
