3.4　字符串与多行原始字符串

Scala的字符串只不过是java.lang.String，可以按照Java的方式使用字符串。不过，Scala还为使用字符串提供了一些额外的便利。

Scala可以自动把String转换成scala.runtime.RichString——这样你就可以无缝地使用诸如capitalize()、lines()和reverse这样一些便捷的方法④。

④不过，这个无缝转换后的结果可能会让你大吃一惊。比如，"mom".reverse == "mom"的结果是false，因为最终比较的是RichString的实例和String的实例。不过，"mom".reverse.toString == "mom"的结果是true。

在Scala里，创建多行字符串真的很容易，只要把多行字符串放在3个双引号间（"""…"""）即可。这是Scala对于here document，或者叫heredoc的支持。这里，我们创建了一个3行长的字符串：

ScalaForTheJavaEyes/MultiLine.scala

val str = """In his famous inaugural speech, John F. Kennedy said
        "And so, my fellow Americans: ask not what your country can do
        for you-ask what you can do for your country." He then proceeded
        to speak to the citizens of the World..."""
println(str)

输出如下：

In his famous inaugural speech, John F. Kennedy said
        "And so, my fellow Americans: ask not what your country can do
        for you-ask what you can do for your country." He then proceeded
        to speak to the citizens of the World...

Scala允许在字符串里嵌入双引号。Scala会将三个双引号里的内容保持原样，在Scala里，称为原始字符串。实际上，Scala处理字符串有些望文生义；如果不想把代码里的缩进带到字符串里，可以用RichString的便捷方法stripMargin()，像这样：

ScalaForTheJavaEyes/MultiLine2.scala

val str = """In his famous inaugural speech, John F. Kennedy said
        |"And so, my fellow Americans: ask not what your country can do
        |for you-ask what you can do for your country." He then proceeded
        |to speak to the citizens of the World...""".stripMargin
println(str)

stripMargin()会去掉先导管道符（|）前所有的空白或控制字符。如果出现在其他地方，而不是每行的开始，就会保留管道符。如果出于某种原因，这个符号有特殊的用途，可以用stripMargin()方法的变体，接收你所选择的其他边缘（margin）字符。上面代码的输出如下：

In his famous inaugural speech, John F. Kennedy said
"And so, my fellow Americans: ask not what your country can do
for you-ask what you can do for your country." He then proceeded
to speak to the citizens of the World...

创建正则表达式时，你会发现原始字符串非常有用。键入和阅读"""\d2:\d2"""可比"\d2:\d2"容易。