Scala Regular Expressions

Scala uses the scala.util.matching package to Regex class to support regular expressions. The following example demonstrates using regular expressions to search for words Scala :

import scala.util.matching.Regex
object Test {
　　　def main(args: Array[String]) {
　　　　　　val pattern = "Scala".r
　　　　　　val str = "Scala is Scalable and cool"
　　　　　　
　　　　　　println(pattern findFirstIn str)
　　　}
}

Execute the above code, the output will be:

$ scalac Test.scala　
$ scala Test
Some(Scala)

The example uses the r() method of the String class to construct a Regex object.

Then use the findFirstIn method to find the first matched item.

If you need to view all the matched items, you can use the findAllIn method.

You can use the mkString( ) method to concatenate the string of regular expression matching results, and you can use the pipe (|) to set different patterns:

import scala.util.matching.Regex
object Test {
　　　def main(args: Array[String]) {
　　　　　　val pattern = new Regex("(S|s)cala")　　//　The first letter can be uppercase S or lowercase s
　　　　　　val str = "Scala is scalable and cool"
　　　　　　
　　　　　　println((pattern findAllIn str).mkString(","))　　　//　Use commas , to connect the returned results
　　　}
}

Execute the above code, the output will be:

$ scalac Test.scala　
$ scala Test
Scala,scala

If you need to replace the matched text with a specified keyword, you can use replaceFirstIn( ) The method to replace the first matched item, using replaceAllIn( ) The method replaces all matched items, for example:

object Test {
　　　def main(args: Array[String]) {
　　　　　　val pattern = "(S|s)cala".r
　　　　　　val str = "Scala is scalable and cool"
　　　　　　
　　　　　　println(pattern replaceFirstIn(str, "Java"))
　　　}
}

Execute the above code, the output will be:

$ scalac Test.scala　
$ scala Test
Java is scalable and cool

Regular expression

Scala's regular expressions inherit the syntax rules of Java, while Java mostly uses the rules of the Perl language.

The following table lists some commonly used regular expression rules:

Regular expression examples

Note that each character in the table above is represented by two backslashes. This is because in Java and Scala, the backslash is an escape character in strings. So if you want to output \, you need to write \\ in the string to get a single backslash. See the following example:

import scala.util.matching.Regex
object Test {
　　　def main(args: Array[String]) {
　　　　　　val pattern = new Regex("abl[ae]\d+")
　　　　　　val str = "ablaw is able1　and cool
　　　　　　
　　　　　　println((pattern findAllIn str).mkString(","))
　　　}
}

Execute the above code, the output will be:

$ scalac Test.scala　
$ scala Test
able1