英文:
Converting List<String> to String using java streams
问题
我在一个 ArrayList 中有一些值，如 Value1，Value2，Value3。现在我需要使用 Java Streams 将它们以 Value1_Value2_Value3 的形式作为单个 String 返回。
我尝试了以下代码，但没有成功：
myList.stream().map((s) -> s + "_").toString();
我还尝试了 collect(toList());，但我不确定如何进一步转换为 String。
请问我该如何实现？
英文:
I have values in an ArrayList as Value1, Value2, Value3.
Now i need to return them in a way as a Single String as Value1_Value2_Value3 using Java Streams.
I've tried this but it didn't work
myList.stream().map((s)->s+"_").toString();
I've also tried collect(toList()); but I'm not sure how to proceed further to convert it to a String.
How can I do it?
答案1
得分: 6
如果您的myList已经包含String（或任何其他CharSequence），则根本不需要使用流，只需调用String.join：
String joined = String.join("_", myList);
否则，您可以使用Collectors.joining从任何旧流中生成String：
String joined = myList.stream().map(Object::toString).collect(Collectors.joining("_"));
英文:
If your myList already contains String (or any other CharSequence), then you don't need streams at all, simply call String.join:
String joined = String.join("_", myList);
Otherwise you can use Collectors.joining to produce String from any old stream:
String joined = myList.stream().map(Object::toString).collect(Collectors.joining("_"));
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论