Java 如何使用新的 1.8 流 API 连接字符串
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How to concatenate a string with the new 1.8 stream API
提问by ZeDonDino
Lets say we have a simple method that should concat all names of a Person collection and return the result string.
假设我们有一个简单的方法，它应该连接 Person 集合的所有名称并返回结果字符串。
public String concantAndReturnNames(final Collection<Person> persons) {
String result = "";
for (Person person : persons) {
result += person.getName();
}
return result;
}
Is there a way to write this code with new stream API forEach function in 1 line?
有没有办法在 1 行中使用新的流 API forEach 函数编写此代码？
采纳答案by Thomas Betous
The official documentation for what you want to do: https://docs.oracle.com/javase/8/docs/api/java/util/stream/Collectors.html
你想要做什么的官方文档：https: //docs.oracle.com/javase/8/docs/api/java/util/stream/Collectors.html
// Accumulate names into a List
List<String> list = people.stream().map(Person::getName).collect(Collectors.toList());
// Convert elements to strings and concatenate them, separated by commas
String joined = things.stream()
.map(Object::toString)
.collect(Collectors.joining(", "));
For your example, you would need to do this:
对于您的示例，您需要执行以下操作：
// Convert elements to strings and concatenate them, separated by commas
String joined = persons.stream()
.map(Person::getName) // This will call person.getName()
.collect(Collectors.joining(", "));
The argument passed to Collectors.joiningis optional.
传递给的参数Collectors.joining是可选的。
