Java 8 lambda 从对象列表创建字符串列表 [英] Java 8 lambda create list of Strings from list of objects

问题描述

我有以下问题:

如何将截取的以下代码转换为 Java 8 lambda 样式?

How can I convert the following code snipped to Java 8 lambda style?

List<String> tmpAdresses = new ArrayList<String>();
for (User user : users) {
    tmpAdresses.add(user.getAdress());
}

不知道从以下几点开始:

Have no idea and started with the following:

List<String> tmpAdresses = users.stream().map((User user) -> user.getAdress());

推荐答案

您需要收集您的流到一个列表:

You need to collect your stream into a List:

List<String> adresses = users.stream()
    .map(User::getAdress)
    .collect(Collectors.toList());

有关不同收集器的更多信息，请访问文档

For more information on the different Collectors visit the documentation

User::getAdress 只是另一种写法 (User user) ->user.getAdress() 也可以写成 user ->user.getAdress() (因为User 类型会被编译器推断出来)

User::getAdress is just another form of writing (User user) -> user.getAdress() which could aswell be written as user -> user.getAdress() (because the type User will be inferred by the compiler)

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