list 按照元素的某個(gè)字段去重

@Data

@AllArgsConstructor

@NoArgsConstructor

public class Student {

private Integer age;

private String name;

}

測試數(shù)據(jù)

List 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 通過tree set 去重

List studentDistinctList = studentList.stream()

.collect(Collectors.collectingAndThen

(Collectors.toCollection(() ->

new TreeSet<>(Comparator.comparing(t -> t.getName()))),

ArrayList::new

)

);

System.out.println(new Gson().toJson(studentDistinctList));

擴(kuò)展distinct 方法去重

List studentDistinct2List = studentList.stream().filter(StreamUtil.distinctByKey(t->t.getName()))

.collect(Collectors.toList());

System.out.println(new Gson().toJson(studentDistinct2List));

工具類

public class StreamUtil {

/**

* https://stackoverflow.com/questions/23699371/java-8-distinct-by-property

* @param keyExtractor

* @param

* @return

*/

public static Predicate distinctByKey(Function super T, ?> keyExtractor) {

Set seen = ConcurrentHashMap.newKeySet();

return t -> seen.add(keyExtractor.apply(t));

}

}

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