Lambda表达式,List对象集合去重

1.创建实体

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@Data @NoArgsConstructor @AllArgsConstructor @Builder public class EmployeeDto {     private String id;     private String name;     private String no_id;     private String dept;     private int year;     private EmpInfoPo info; }

　　

2.List实体数据

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{"dept":"研发部1","id":"001","name":"员工1号","no_id":"YF001","year":2} {"dept":"研发部2","id":"002","name":"员工2号","no_id":"YF001","year":5} {"dept":"研发部3","id":"003","name":"员工3号","no_id":"YF001","year":7} {"dept":"研发部4","id":"004","name":"员工4号","no_id":"YF001","year":6} {"dept":"研发部5","id":"005","name":"员工5号","no_id":"YF001","year":4} {"dept":"研发部6","id":"006","name":"员工1号","no_id":"YF001","year":2}

　　

3.Lambda方式去重

集合方式排序、stream方式排序对比
Collectors.collectingAndThen()数据流转处理函数
distinctByKey()自定义比较器

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/**  * 函数去重  利用TreeSet无重复特性  * collect 收集器  * Collectors 收集器的方法  */ public static void exceptRepeatV1(List<EmployeeDto> employeeList){     ArrayList<EmployeeDto> collect = employeeList             .stream()             .collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(EmployeeDto::getName))), ArrayList::new));     print(collect); }   /**  * 自定义方式去重  * @param employeeList  */ public static void exceptRepeatV2(List<EmployeeDto> employeeList){     List<EmployeeDto> collect = employeeList.stream()             .filter(distinctByKey(e -> e.getName()))             .collect(Collectors.toList());     print(collect); }   /**  * 自定义比较方法  * @param keyExtractor  * @param <T>  * @return  */ private static <T> Predicate<T> distinctByKey(Function<? super T,?> keyExtractor){     Map<Object,Boolean> map=new ConcurrentHashMap<>();     return t -> map.putIfAbsent(keyExtractor.apply(t),Boolean.TRUE)==null; }

　　

转载自：https://blog.csdn.net/Oaklkm/article/details/127074712