List转Map

1，List中的引用类型转Map

引入的Jar包:

　import java.util.Map;   
　import com.google.common.base.Function;
　import com.google.common.collect.Maps;

Maven依赖:　　

<dependency>
  <groupId>com.google.guava</groupId>
  <artifactId>guava</artifactId>
  <version>19.0</version>
</dependency>

具体实现:

List<UserDO> userDOs = new ArrayList<>();
Map<Long,UserDO> mapUsers = Maps.uniqueIndex(userDOs, new Function <UserDO,Long> () {  
　　public Long apply(UserDO from) {  
　　　　return from.getUid();
}});

List<UserVo> userVos = getUserInfoById(userIds);
Map<String,UserVo> mapUsers = Maps.uniqueIndex(userVos, new Function<UserVo,String>() {
    @Override
    public String apply(UserVo input) {
        return input.getId();
    }
});