Matcher

java.util.regex

Class Matcher

• java.lang.Object
• • java.util.regex.Matcher

• All Implemented Interfaces:

  MatchResult

  ---

  
  

  public final class Matcher
  extends Object
  implements MatchResult

  An engine(引擎) thatperforms(执行) matchoperations(操作) on acharacter sequence byinterpreting(解释) aPattern.

  A matcher is created from a pattern by invoking the pattern'smatcher method. Once created, a matcher can be used to perform threedifferent(不同的)kinds(种类) of match operations:

  • The matches method attempts(试图) to match the entire(整个的) input sequence against the pattern.

  • The lookingAt method attempts to match the input sequence, starting at the beginning, against the pattern.

  • The find method scans the input sequence looking for the next subsequence that matches the pattern.

  Each of these methods returns a boolean indicating success orfailure(失败). Moreinformation(信息) about a successful match can be obtained(获得) by querying the state of the matcher.

  A matcher finds matches in a subset(子集) of its input called theregion. By default, theregion(区域)contains(包含) all of the matcher's input. The region can be modified(修改的) via通过) theregion method andqueried(查询的)via theregionStart and regionEnd methods. The way that the regionboundaries(边界)interact(交互) with some patternconstructs(构造) can be changed. SeeuseAnchoringBounds anduseTransparentBounds for moredetails(详细资料).

  This class also defines(定义) methods for replacing matched subsequences with new strings whose contents can, if desired(需要), becomputed(计算) from the match result. TheappendReplacement andappendTail methods can be used in tandem(一前一后地) in order tocollect(收集) the result into anexisting(现存的) string buffer, or the more convenient(方便的)replaceAll method can be used to create a string in which every matching subsequence in the input sequence is replaced.

  The explicit(显式) state of a matcher includes the start and end indices(索引) of the mostrecent(最近的) successful match. It also includes the start and end indices of the input subsequence captured(捕获) by eachcapturing group in the pattern as well as a total count of such subsequences. As a convenience(方便), methods are also provided(提供) for returning these captured(捕获) subsequences in string form.

  The explicit state of a matcher is initially undefined; attempting(尝试)to query any part(部分) of it before a successful match will cause(造成) anIllegalStateException to be thrown. The explicit state of a matcher is recomputed(重新计算的) by every match operation.

  The implicit(隐式的) state of a matcher includes the input character sequence as well as theappend position(位置), which is initially(开始) zero and is updated by theappendReplacement method.

  A matcher may be reset(重置) explicitly by invoking itsreset() method or, if a new input sequence is desired(需要), itsreset(CharSequence) method. Resetting a matcher discards(丢弃) its explicit state information(信息) and sets the append position(位置) to zero.

  Instances of this class are not safe for use by multiple concurrent threads(多线程并发).