一、Lists.partition(List<T> list, int size)

将 list 集合按指定长度进行切分，返回新的List<List<T>>集合。

import com.google.common.collect.Lists;
import org.junit.Test;
import java.util.List;public class ListDemo {@Testpublic void partition() {List<Integer> souList = Lists.newArrayList(1, 2, 3, 4, 5, 6, 7, 8);List<List<Integer>> tarList = Lists.partition(souList, 5);
//        souList.clear();//clear souList，tarList will be emptySystem.out.println(tarList);  //[[1, 2, 3, 4, 5], [6, 7, 8]]}
}

二、Lists.transform()

1️⃣把一个 List<Map<String,String>> 中的所有 map 对应某个 key 的 value 值取出来返回一个新的 list。

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import org.junit.Test;import java.util.List;
import java.util.Map;public class ListDemo {@Testpublic void transform() {Map<String, String> map = Maps.newHashMap();map.put("a", "a-1");map.put("b", "b-1");System.out.println("map:" + map);//map:{a=a-1, b=b-1}Map<String, String> map2 = Maps.newHashMap();map2.put("a", "a-2");map2.put("c", "c-1");System.out.println("map2:" + map2);//map2:{a=a-2, c=c-1}List<Map<String, String>> list = Lists.newArrayList();list.add(map);list.add(map2);System.out.println("list:" + list);//list:[{a=a-1, b=b-1}, {a=a-2, c=c-1}]List<String> list3 = Lists.transform(list, xxp -> xxp.get("a"));System.out.println(list3);//[a-1, a-2]list3.forEach(s -> System.out.println(s));}
}

2️⃣可以使用 Lists.transform 把对象 list 中的某个属性取出来返回一个新的 list。

@Data
public class Person {private Integer age;private String name;public static void main(String[] args) {List<Person> sourList = Lists.newArrayList(new Person(1, "a"), new Person(2, "b"), new Person(3, "c"));//source:[Person(age=1, name=a), Person(age=2, name=b), Person(age=3, name=c)]System.out.println("source:" + sourList);List<String> tarList = Lists.transform(sourList, xxp -> xxp.getName());//a b ctarList.forEach(s -> System.out.println(s));System.out.println("============");sourList.forEach(wg -> {wg.setName("temp");});//[temp, temp, temp]tarList.forEach(s -> System.out.println(s));}
}