如何实现java8 list按照元素的某个字段去重

list 按照元素的某个字段去重

@data
@allargsconstructor
@noargsconstructor
public 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://*.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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