对List<实体类>重复值的操作

判断是否有重复：（Boolean）

public Boolean JudgeStopWatchValue(List<StopWatchValue> stopWatchValues) {
        AtomicReference<Boolean> flag = new AtomicReference<>(true);
        //判断码值编码是否重复
        // 根据指定属性分组，并统计数量（key：指定属性，value：数量）
        Map<Object, Long> mapGroup = stopWatchValues.stream().collect(Collectors.groupingBy(StopWatchValue::getcValue, Collectors.counting()));
        // 筛选Map中value大于1的key
        Stream<Object> stringStream = mapGroup.entrySet().stream().filter(entry -> entry.getValue() > 1).map(Map.Entry::getKey);
        stringStream.forEach(str -> {
            if (str!=null){
                flag.set(false);
            }
        });
        return flag.get();
    }

查重：

public static void main(String[] args) {
		 Person person1 = new Person("小刘", 24, "男");
        Person person2 = new Person("小贺", 18, "女");
        Person person3 = new Person("小袁", 18, "女");
        Person person4 = new Person("小李", 21, "男");
        Person person5 = new Person("小子", 21, "男");
        List<Person> persons = Arrays.asList(person1, person2, person3, person4,person5);

        // 根据指定属性分组，并统计数量（key：指定属性，value：数量）
        Map<Object, Long> mapGroup = persons.stream().collect(Collectors.groupingBy(person -> person.getAge(), Collectors.counting()));
        System.out.println(mapGroup.toString());

        // 筛选Map中value大于1的key
        Stream<Object> stringStream = mapGroup.entrySet().stream().filter(entry -> entry.getValue() > 1).map(entry -> entry.getKey());
        System.out.print("重复的数据：{ ");
        stringStream.forEach(str -> {
            System.out.print(str + " ");
        });
        System.out.println("}");
	}

去重：

public static void main(String[] args) {
        Map map1=new HashMap();
        Map map2=new HashMap();
        Map map3=new HashMap();
        map1.put("name","Jam");
        map1.put("age","20");
        map2.put("name","Jam");
        map2.put("age","20");
        map3.put("name","Jam");
        map3.put("age","20");
        List testList=new ArrayList();
        testList.add(map1);
        testList.add(map2);
        testList.add(map2);
        System.out.println("去重前");
        System.out.println(testList);
        //java8去重
        testList= (List) testList.stream().distinct().collect(Collectors.toList());
        System.out.println("去重后");
        System.out.println(testList);
    }