Java 8 lambda 从对象列表创建字符串列表
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Java 8 lambda create list of Strings from list of objects
提问by LStrike
I have the following qustion:
我有以下问题：
How can I convert the following code snipped to Java 8 lambda style?
如何将截取的以下代码转换为 Java 8 lambda 样式？
List<String> tmpAdresses = new ArrayList<String>();
for (User user : users) {
tmpAdresses.add(user.getAdress());
}
Have no idea and started with the following:
不知道并从以下开始：
List<String> tmpAdresses = users.stream().map((User user) -> user.getAdress());
采纳答案by Lino
You need to collectyour stream into a List:
您需要将collect流转换为列表：
List<String> adresses = users.stream()
.map(User::getAdress)
.collect(Collectors.toList());
For more information on the different Collectorsvisit the documentation
有关不同Collectors访问文档的更多信息
User::getAdressis just another form of writing (User user) -> user.getAdress()which could aswell be written as user -> user.getAdress()(because the type Userwill be inferred by the compiler)
User::getAdress只是另一种写法(User user) -> user.getAdress()，也可以写成user -> user.getAdress()（因为User编译器会推断出类型）
回答by Piotr R
It is extended your idea:
它扩展了你的想法：
List<String> tmpAdresses = users.stream().map(user ->user.getAdress())
.collect(Collectors.toList())
回答by Oomph Fortuity
One more way of using lambda collectors like above answers
使用上述答案的 lambda 收集器的另一种方法
List<String> tmpAdresses= users
.stream()
.collect(Collectors.mapping(User::getAddress, Collectors.toList()));
