利用java8的流和lambda表达式能很方便的对list对象进行去重
而且不会造成代码入侵
插播：Java8 对List进行求和、分组、提取对象单个属性：https://www.jianshu.com/p/c71eaeaaf30c
下面的例子仅供参考
github：https://github.com/hisenyuan
package com.hisen.collection.list.duplicate;
import com.alibaba.rocketmq.shade.com.alibaba.fastjson.JSON;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Collectors;
/**
* @author hisenyuan
* @time 2018/4/19 14:06
* @description list对象根据属性去重 lambda + stream
*/
public class ListDuplicateTest {
public static void main(String[] args) {
List<Person> list = new ArrayList<>();
for (int i = 0; i < 100; i++) {
Person person = new Person();
person.setAge(10);
person.setName("hsien");
person.setWeight(i);
list.add(person);
}
Person bean = new Person();
bean.setName("hisenyuan");
bean.setAge(33);
bean.setWeight(65);
list.add(bean);
List<Person> collect = list.stream().filter(distinctByKey(Person::getName))
.collect(Collectors.toList());
System.out.println(JSON.toJSONString(collect));
}
/**
* 函数式接口 T -> bollean
* @param keyExtractor
* @param <T>
* @return
*/
public static <T> Predicate<T> distinctByKey(Function<? super T, ?> keyExtractor) {
ConcurrentHashMap<Object, Boolean> map = new ConcurrentHashMap<>(16);
return t -> map.putIfAbsent(keyExtractor.apply(t),Boolean.TRUE) == null;
// 这个也可以，不过感觉效率要低一些，线程不是那么安全
// Set<Object> seen = ConcurrentHashMap.newKeySet();
// return t -> seen.add(keyExtractor.apply(t));
}
/**
* 内部类
*/
static class Person {
private int age;
private String name;
private int weight;
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getWeight() {
return weight;
}
public Person() {
}
public void setWeight(int weight) {
this.weight = weight;
}
}
}
