java8流连接映射输出到字符串返回java.util.stream.ReferencePipeline

嗨，我想从对象steam中提取和格式化属性，并将它们连接到一个新字符串中

前

我得到

java.util.stream.ReferencePipeline$3@396555a1

而不是

The user name is john and his lastname is rush
The user name is peter and his lastname is gabriel

提前谢谢

java.util.stream.ReferencePipeline$3@396555a1

是在执行

map

操作之前尝试打印您创建的

流

的结果

您希望

收集

到目前为止映射的用户名，同时使用

\n

分隔符加入

String users = memberNames.stream()
        .map(user -> String.format("The user name is %s and his lastname is %s", user.name, user.lastname))
        .collect(Collectors.joining("\n"));
System.out.println(users); // to print them all at once

---

我认为您的代码中有一个小错误：

List memberNames

而不是

List memberNames

java.util.stream.ReferencePipeline$3@396555a1

String users = memberNames.stream()
        .map(user -> String.format("The user name is %s and his lastname is %s", user.name, user.lastname))
        .collect(Collectors.joining("\n"));
System.out.println(users); // to print them all at once