Java - 将引号附加到数组中的字符串并连接数组中的字符串 [英] Java - Append quotes to strings in an array and join strings in an array

问题描述

我想将双引号附加到数组中的字符串，然后将它们作为单个字符串连接（保留引号）。有没有这样做的字符串库？我在Google番石榴中尝试过Apache commons StringUtils.join和Joiner类，但找不到附加双引号的任何内容。

I would like to append double quotes to strings in an array and then later join them as a single string (retaining the quotes). Is there any String library which does this? I have tried Apache commons StringUtils.join and the Joiner class in Google guava but couldn't find anything that appends double quotes.

我的输入将是一个数组，如下所述：

My input would be an array as mentioned below:

String [] listOfStrings = {"day", "campaign", "imps", "conversions"};

所需的输出应如下所述：

Required output should be as mentioned below:

String output = "\"day\", \"campaign\", \"imps\", \"conversions\"";

我知道我可以遍历数组并附加引号。但是如果有的话，我想要一个更清洁的解决方案。

I know I can loop through the array and append quotes. But I would like a more cleaner solution if there is one.

推荐答案

使用Java 8 +

Java 8有 Collectors.joining（） 及其重载。它还有 String.join 。

具有可重复使用的功能

Function<String,String> addQuotes = s -> "\"" + s + "\"";

String result = listOfStrings.stream()
  .map(addQuotes)
  .collect(Collectors.joining(", "));

没有任何可重复使用的功能

String result = listOfStrings.stream()
  .map(s -> "\"" + s + "\"")
  .collect(Collectors.joining(", "));

最短（虽然有点hackish）

Shortest (somewhat hackish, though)

String result = listOfStrings.stream()
  .collect(Collectors.joining("\", \"", "\"", "\""));

使用 String.join

非常hackish。不要在名为 wrapWithQuotesAndJoin 的方法中使用除外。

Using String.join

Very hackish. Don't use except in a method called wrapWithQuotesAndJoin.

String result = listOfString.isEmpty() ? "" : "\"" + String.join("\", \"", listOfStrings) + "\"";

旧版本的Java

你自己帮忙并使用图书馆。立即考虑番石榴。

Function<String,String> addQuotes = new Function<String,String>() {
  @Override public String apply(String s) {
    return new StringBuilder(s.length()+2).append('"').append(s).append('"').toString();
  }
};
String result = Joiner.on(", ").join(Iterables.transform(listOfStrings, addQuotes));

没有图书馆

No libraries

String result;
if (listOfStrings.isEmpty()) {
  result = "";
} else {
  StringBuilder sb = new StringBuilder();
  Iterator<String> it = listOfStrings.iterator();
  sb.append('"').append(it.next()).append('"'); // Not empty
  while (it.hasNext()) {
    sb.append(", \"").append(it.next()).append('"');
  }
  result = sb.toString();
}

注意：所有解决方案都假设 listOfStrings 是一个 List< String> 而不是 String [] 。您可以使用 Arrays.asList将 String [] 转换为 List< String> arrayOfStrings）。您可以使用 Arrays.stream直接从 String [] 获取 Stream< String> （arrayOfString）。

Note: all the solutions assume that listOfStrings is a List<String> rather than a String[]. You can convert a String[] into a List<String> using Arrays.asList(arrayOfStrings). You can get a Stream<String> directly from a String[] using Arrays.stream(arrayOfString).

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