java8判断list＜Map＜String,Object＞＞ 对象某个属性的值是否重复_java 判断list

java8判断list<Map<String,Object>> 对象某个属性的值是否重复

	List<Map<String,Object>> list = new ArrayList<>();
        Map<String,Object> m1 = new HashMap<>();
        m1.put("a","1");
        m1.put("b","z");
        Map<String,Object> m2 = new HashMap<>();
        m2.put("a","1");
        m2.put("b","y");
        Map<String,Object> m3 = new HashMap<>();
        m3.put("a","2");
        m3.put("b","j");
        list.add(m1);
        list.add(m2);
        list.add(m3);
        Map<Object, Long> collect2 = list.stream().collect(
                Collectors.groupingBy( map -> MapUtils.getMapStrdef(map,"a","") , Collectors.counting()));
        List<Object> collect3 = collect2.keySet().stream().
                filter(key -> collect2.get(key) > 1).collect(Collectors.toList());


        System.out.println("方法2-重复的姓名 ： "+collect3);
        
        方法2-重复的姓名 ： [1]
        
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List 取重复值
List list1 = Arrays.asList(“a”,“b”,“a”,“c”,“d”,“b”);
List repeatList = list1.stream().collect(Collectors.groupingBy(e -> e, Collectors.counting()))
.entrySet().stream().filter(e -> e.getValue() > 1)
.map(Map.Entry::getKey).collect(Collectors.toList());

[a, b]