Scala中正則表達式以及與模式匹配結合(多種方式)

 更新時間:2019年06月17日 15:06:32   作者:易悠   我要評論
這篇文章主要介紹了Scala中正則表達式以及與模式匹配結合,本文給大家介紹了多種模式匹配方式,需要的朋友可以參考下

正則表達式

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

說明:.r()方法簡介:Scala中將字符串轉換為正則表達式

 /** 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()方法返回遍歷所有匹配項的迭代器
 for(matchString <- numPattern.findAllIn("99345 Scala,22298 Spark"))
  println(matchString)

說明:findAllIn(…)函數簡介

/** 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)

這里寫圖片描述

模式匹配二

 //找到首個匹配項
 println(numberPattern.findFirstIn("99ss java, 222 spark,333 hadoop"))

這里寫圖片描述

模式匹配三

//數字和字母的組合正則表達式
 val numitemPattern="""([0-9]+) ([a-z]+)""".r
 val numitemPattern(num, item)="99 hadoop"

這里寫圖片描述

模式匹配四

 //數字和字母的組合正則表達式
 val numitemPattern="""([0-9]+) ([a-z]+)""".r
 val line="93459 spark"
 line match{
  case numitemPattern(num,blog)=> println(num+"\t"+blog)
  case _=>println("hahaha...")
 }

這里寫圖片描述

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

這里寫圖片描述

本節所有程序源碼

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//"""原生表達
 val numPattern="[0-9]+".r
 val numberPattern="""\s+[0-9]+\s+""".r
 //findAllIn()方法返回遍歷所有匹配項的迭代器
 for(matchString <- numPattern.findAllIn("99345 Scala,22298 Spark"))
  println(matchString)
 //找到首個匹配項
 println(numberPattern.findFirstIn("99ss java, 222 spark,333 hadoop"))
 //數字和字母的組合正則表達式
 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...")
 }
 }
}

這里寫圖片描述

總結

以上所述是小編給大家介紹的Scala中正則表達式以及與模式匹配結合(多種方式),希望對大家有所幫助,如果大家有任何疑問歡迎給我留言,小編會及時回復大家的!

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