list 按照元素的某个字段去重

@Data@AllArgsConstructor@NoArgsConstructorpublic class Student {private Integer age;private String name;}

测试数据

List<Student> studentList = Lists.newArrayList();studentList.add(new Student(28, "river"));studentList.add(new Student(12, "lucy"));studentList.add(new Student(33, "frank"));studentList.add(new Student(33, "lucy"));

java8 通过tree set 去重

List<Student> studentDistinctList = studentList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() ->new TreeSet<>(Comparator.comparing(t -> t.getName()))),ArrayList::new));System.out.println(new Gson().toJson(studentDistinctList));

扩展distinct 方法去重

List<Student> studentDistinct2List = studentList.stream().filter(StreamUtil.distinctByKey(t->t.getName())).collect(Collectors.toList());System.out.println(new Gson().toJson(studentDistinct2List));

工具类

public class StreamUtil {/*** https://stackoverflow.com/questions/23699371/java-8-distinct-by-property* @param keyExtractor* @param <T>* @return*/public static <T> Predicate<T> distinctByKey(Function<? super T, ?> keyExtractor) {Set<Object> seen = ConcurrentHashMap.newKeySet();return t -> seen.add(keyExtractor.apply(t));}}

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