如何在Java中高效创建多行字符串？

Java 支持多行字符串吗？

对于那些熟悉 Perl 的人来说，“here-document”是一个在其中创建多行字符串的有用工具。源代码。然而，在 Java 中，在每行上使用引号和加号手动连接字符串可能会非常乏味且麻烦。

虽然 Java 中没有与“here-document”语法直接等效的语法，但有几种替代方法考虑有效地创建多行字符串。

1.使用加号运算符 ( ) 连接字符串

最简单的方法是使用加号运算符 ( ) 手动连接字符串。这涉及使用字符串文字 ""n"" 根据需要显式添加换行符：

String s = "It was the best of times, it was the worst of times\n"
         + "it was the age of wisdom, it was the age of foolishness\n"
         + "it was the epoch of belief, it was the epoch of incredulity\n"
         + "it was the season of Light, it was the season of Darkness\n"
         + "it was the spring of hope, it was the winter of despair\n"
         + "we had everything before us, we had nothing before us";

2。 StringBuilder.append()

StringBuilder 类提供了一个名为append() 的方法，可用于将字符串或其他数据附加到字符串生成器。虽然此技术可能看起来不如使用加号运算符简洁，但它提供了某些优点，例如增强的性能和线程安全性。

StringBuilder sb = new StringBuilder();
sb.append("It was the best of times, it was the worst of times");
sb.append("it was the age of wisdom, it was the age of foolishness");
// ...
String s = sb.toString();

3. String.join()

在 Java 8 中引入，String.join() 允许使用指定的分隔符将多个字符串组合成单个字符串。要创建多行字符串，可以设置分隔符来表示所需的换行符：

String s = String.join("\n"
         , "It was the best of times, it was the worst of times"
         , "it was the age of wisdom, it was the age of foolishness"
         // ...
);

4。 String.format()

String.format() 是一个基于模式格式化字符串的强大工具。它还可用于通过将换行符合并到格式模式中来创建多行字符串：

String s = String.format("%s\n%s\n%s\n%s\n%s\n%s"
         , "It was the best of times, it was the worst of times"
         , "it was the age of wisdom, it was the age of foolishness"
         // ...
);

5。存储在文本文件中

对于特别大的字符串，将内容存储在单独的文本文件中，然后将文件的内容读入字符串中可能会很有帮助。这种方法可以帮助避免带有大字符串文字的类文件膨胀。

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