在 Java 中加入字符串集合的首选习语 [英] Preferred Idiom for Joining a Collection of Strings in Java

问题描述

给定一个字符串集合，如何在不使用外部库的情况下用纯 Java 将它们连接起来?

Given a Collection of Strings, how would you join them in plain Java, without using an external Library?

给定这些变量:

Collection<String> data = Arrays.asList("Snap", "Crackle", "Pop");
String separator = ", ";
String joined; // let's create this, shall we?

这就是我在 Guava 中的做法:

This is how I'd do it in Guava:

joined = Joiner.on(separator).join(data);

在 Apache Commons/Lang 中:

joined = StringUtils.join(data, separator);

但是在纯 Java 中，真的没有比这更好的方法了吗?

But in plain Java, is there really no better way than this?

StringBuilder sb = new StringBuilder();
for(String item : data){
    if(sb.length()>0)sb.append(separator);
    sb.append(item);
}
joined = sb.toString();

推荐答案

我会说最好这样做的方法(如果最好的你不是指最简洁")而不使用Guava 正在使用 Guava 内部使用的技术，对于您的示例，它看起来像这样:

I'd say the best way of doing this (if by best you don't mean "most concise") without using Guava is using the technique Guava uses internally, which for your example would look something like this:

Iterator<String> iter = data.iterator();
StringBuilder sb = new StringBuilder();
if (iter.hasNext()) {
  sb.append(iter.next());
  while (iter.hasNext()) {
    sb.append(separator).append(iter.next());
  }
}
String joined = sb.toString();

这不需要在迭代时进行布尔检查，也不需要对字符串进行任何后处理.

This doesn't have to do a boolean check while iterating and doesn't have to do any postprocessing of the string.

这篇关于在 Java 中加入字符串集合的首选习语的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！