Scala中正则表达式以及与模式匹配结合

正则表达式

    //"""原生表达    val regex="""([0-9]+)([a-z]+)""".r    val numPattern="[0-9]+".r    val numberPattern="""\s+[0-9]+\s+""".r

• 说明：.r()方法简介：Scala中将字符串转换为正则表达式

  /** You can follow a string with `.r`, turning it into a `Regex`. E.g.   *   *  `"""A\w*""".r`   is the regular expression for identifiers starting with `A`.   */  def r: Regex = r()

模式匹配一

    //findAllIn()方法返回遍历所有匹配项的迭代器    for(matchString <- numPattern.findAllIn("99345 Scala,22298 Spark"))      println(matchString)

• 说明：findAllIn(…)函数简介

  /** Return all non-overlapping matches of this `Regex` in the given character    *  sequence as a [[scala.util.matching.Regex.MatchIterator]],   *  which is a special [[scala.collection.Iterator]] that returns the   *  matched strings but can also be queried for more data about the last match,   *  such as capturing groups and start position.   *    *  A `MatchIterator` can also be converted into an iterator   *  that returns objects of type [[scala.util.matching.Regex.Match]],   *  such as is normally returned by `findAllMatchIn`.   *    *  Where potential matches overlap, the first possible match is returned,   *  followed by the next match that follows the input consumed by the   *  first match:   *   *  {{{   *  val hat  = "hat[^a]+".r   *  val hathaway = "hathatthattthatttt"   *  val hats = (hat findAllIn hathaway).toList                     // List(hath, hattth)   *  val pos  = (hat findAllMatchIn hathaway map (_.start)).toList  // List(0, 7)   *  }}}   *   *  To return overlapping matches, it is possible to formulate a regular expression   *  with lookahead (`?=`) that does not consume the overlapping region.   *   *  {{{   *  val madhatter = "(h)(?=(at[^a]+))".r   *  val madhats   = (madhatter findAllMatchIn hathaway map {   *    case madhatter(x,y) => s"$x$y"   *  }).toList                                       // List(hath, hatth, hattth, hatttt)   *  }}}   *   *  Attempting to retrieve match information before performing the first match   *  or after exhausting the iterator results in [[java.lang.IllegalStateException]].   *  See [[scala.util.matching.Regex.MatchIterator]] for details.   *   *  @param source The text to match against.   *  @return       A [[scala.util.matching.Regex.MatchIterator]] of matched substrings.   *  @example      {{{for (words <- """\w+""".r findAllIn "A simple example.") yield words}}}   */  def findAllIn(source: CharSequence) = new Regex.MatchIterator(source, this, groupNames)

模式匹配二

    //找到首个匹配项    println(numberPattern.findFirstIn("99ss java, 222 spark,333 hadoop"))

模式匹配三

    //数字和字母的组合正则表达式    val numitemPattern="""([0-9]+) ([a-z]+)""".r    val numitemPattern(num, item)="99 hadoop"

模式匹配四

    //数字和字母的组合正则表达式    val numitemPattern="""([0-9]+) ([a-z]+)""".r    val line="93459 spark"    line match{      case numitemPattern(num,blog)=> println(num+"\t"+blog)      case _=>println("hahaha...")    }

val line="93459h spark"    line match{      case numitemPattern(num,blog)=> println(num+"\t"+blog)      case _=>println("hahaha...")    }

本节所有程序源码

package kmust.hjr.learningScala19/** * Created by Administrator on 2015/10/17. */object RegularExpressOps {  def main(args:Array[String]):Unit={    val regex="""([0-9]+)([a-z]+)""".r//"""原生表达    val numPattern="[0-9]+".r    val numberPattern="""\s+[0-9]+\s+""".r    //findAllIn()方法返回遍历所有匹配项的迭代器    for(matchString <- numPattern.findAllIn("99345 Scala,22298 Spark"))      println(matchString)    //找到首个匹配项    println(numberPattern.findFirstIn("99ss java, 222 spark,333 hadoop"))    //数字和字母的组合正则表达式    val numitemPattern="""([0-9]+) ([a-z]+)""".r    val numitemPattern(num, item)="99 hadoop"    val line="93459h spark"    line match{      case numitemPattern(num,blog)=> println(num+"\t"+blog)      case _=>println("hahaha...")    }  }}

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