这篇文章主要介绍了Scala中正则表达式以及与模式匹配结合,本文给大家介绍了多种模式匹配方式，需要的朋友可以参考下
正文
Scala中正则表达式以及与模式匹配结合(多种方式)
正则表达式
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//"""原生表达val regex="""([0-9]+)([a-z]+)""".rval numPattern="[0-9]+".rval 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
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/** 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
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//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
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/** 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
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//找到首个匹配项println(numberPattern.findFirstIn("99ss java, 222 spark,333 hadoop")) |
模式匹配三
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//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
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//数字和字母的组合正则表达式val numitemPattern="""([0-9]+) ([a-z]+)""".rval line="93459 spark"line match{ case numitemPattern(num,blog)=> println(num+"\t"+blog) case _=>println("hahaha...")} |
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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
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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...") } }} |
总结
以上所述是小编给大家介绍的Scala中正则表达式以及与模式匹配结合(多种方式)，希望对大家有所帮助，如果大家有任何疑问欢迎给我留言，小编会及时回复大家的！
原文链接：https://blog.csdn.net/yizheyouye/article/details/49204595
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