java里面List＜Object＞转map，List＜String＞

比较常见的工具类，使用guava和java里面的stream实现

package cn.mark.tool;
 
import cn.hutool.json.JSONUtil;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
 
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
 
/**
 * 
 * list转map，
 * 
 *
 * @author : mark
 * @since : 2022/11/3 19:35
 */
public class UTest {
 
    public static void main(String[] args) {
        List<Demo> list = new ArrayList<>();
        Demo demo = new Demo();
        demo.setId("2222");
        demo.setName("tom");
        list.add(demo);
        List<String> orderList = list.stream().map(Demo::getId).collect(Collectors.toList());
 
        System.out.println(orderList);
 
        ImmutableMap<String, Demo> orderMap = Maps.uniqueIndex(list.iterator(), Demo::getId);
        System.out.println(JSONUtil.toJsonStr(orderMap));
 
    }
 
    public static class Demo {
        private String id;
        private String name;
 
        public String getId() {
            return id;
        }
 
        public void setId(String id) {
            this.id = id;
        }
 
        public String getName() {
            return name;
        }
 
        public void setName(String name) {
            this.name = name;
        }
    }
}

执行结果如下

[2222]
{"2222":{"id":"2222","name":"tom"}}