放置 Set<String> 内容的最快方法到一个用空格分隔的单词的字符串? [英] Fastest way to put contents of Set<String> to a single String with words separated by a whitespace?
问题描述
我有几个 Set
并且想将它们中的每一个转换为单个 String
,其中原始 Set
由空格"分隔.天真的第一种方法是这样做
I have a few Set<String>
s and want to transform each of these into a single String
where each element of the original Set
is separated by a whitespace " ".
A naive first approach is doing it like this
Set<String> set_1;
Set<String> set_2;
StringBuilder builder = new StringBuilder();
for (String str : set_1) {
builder.append(str).append(" ");
}
this.string_1 = builder.toString();
builder = new StringBuilder();
for (String str : set_2) {
builder.append(str).append(" ");
}
this.string_2 = builder.toString();
谁能想到更快、更漂亮或更有效的方法来做到这一点?
Can anyone think of a faster, prettier or more efficient way to do this?
推荐答案
使用 commons/lang 你可以使用 StringUtils.join:
String str_1 = StringUtils.join(set_1, " ");
为简洁起见,您真的无法击败它.
You can't really beat that for brevity.
更新:
重新阅读这个答案,我现在更喜欢关于 Guava's Joiner 的另一个答案.事实上,这些天我不去接近 apache commons.
Re-reading this answer, I would prefer the other answer regarding Guava's Joiner now. In fact, these days I don't go near apache commons.
另一个更新:
Java 8 引入了方法 String.join()
Java 8 introduced the method String.join()
String joined = String.join(",", set);
虽然这不像 Guava 版本那样灵活,但当你的类路径上没有 Guava 库时它很方便.
While this isn't as flexible as the Guava version, it's handy when you don't have the Guava library on your classpath.
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