Lists.transform的使用

Lists.transform：能够轻松的从一种类型的list转换为另一种类型的list。

	Map<String,String> map = Maps.newHashMap();
        map.put("a","testa");
        map.put("b","test2");
        map.put("c","test3");
        Map<String,String> map = Maps.newHashMap();
        map2.put("a","test3");
        map2.put("b","testb");
        map2.put("d","testc");
        List<Map<String,String>> list2=Lists.newArrayList();
        list2.add(map);
        list2.add(map2);
        List<String> list3=Lists.transform(list2,s->s.get("a"));
        list3.forEach(s -> System.out.println(s));

结果如下

testa
testa2

还有采坑的，得需要注意下

  List<User> userdbs = Lists.newArrayList(new User("zhangsan", "20"),
	new User("lisi", "24"), new User("wangwu", "30"));

        List<UserVo> userVos = Lists.transform(userdbs,xx ->{
            return new UserVo(xx.getName(),xx.getId());
        });
        List<UserVo> userVosNew =userdbs.stream().map(xx->{
		 return new UserVo(xx.getName(),xx.getId());
        }).collect(Collectors.toList());

        userdbs.forEach(xx->xx.setName(xx.getName()+"_test"));
        userVos.forEach(xx -> System.out.println(xx.getName()));
        System.out.println("=======change lambda 方式");
        userVosNew.forEach(xx -> System.out.println(xx.getName()));

结果

zhangsan_test
lisi_test
wangwu_test
=======change lambda 方式
zhangsan
lisi
wangwu

引用实体如下 ，未添加set,get方法

class UserVo{
private String id;
private String name;
}
class User{
private String id;
private String name;
}

对原数据集users的修改会直接影响到Lists.transform方法返回的结果userVos， 解决方案还是用 lambda 把方便快捷

参考https://blog.csdn.net/mnmlist/article/details/53870520