Java Matcher 翻译

 

java.util.regex

Class Matcher

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

• All Implemented Interfaces:

  MatchResult

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  public final class Matcher
  extends Object
  implements MatchResult

  An engine(引擎) that performs(执行) match operations on a character sequence by interpreting(解释) a Pattern.

  A matcher is created from a pattern by invoking the pattern's matcher method. Once created, a matcher can be used to perform three different kinds of match operations:

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

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

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

  Each of these methods returns a boolean indicating(表明) success or failure. More information about a successful match can be obtained(获得) by querying the state of the matcher.

  A matcher finds matches in a subset of its input called the region. By default, the region contains all of the matcher's input. The region can be modified via the region method and queried via the regionStart and regionEnd methods. The way that the region boundaries(边界) interact(互相作用) with some pattern constructs(构造) can be changed. See useAnchoringBounds and useTransparentBounds for more details.

  This class also defines methods for replacing matched subsequences with new strings whose contents can, if desired(需求), be computed from the match result. The appendReplacement and appendTail methods can be used in tandem(串联) in order to collect(汇集) the result into an existing 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(明确的) state of a matcher includes the start and end indices(目录) of the most recent(最近的) successful match. It also includes the start and end indices of the input subsequence captured(捕获) by each capturing group in the pattern as well as(和…一样) a total count of such(这样的) subsequences. As a convenience(方便), methods are also provided for returning these captured(捕获) subsequences in string form(格式).

  The explicit(明确的) state of a matcher is initially(最初的) undefined; attempting(试图) to query any part of it before a successful match will cause(导致) an IllegalStateException to be thrown. The  explicit(明确的) state of a matcher is recomputed(验算) by every match operation.

  The implicit(隐式) state of a matcher includes the input character sequence as well as the append position, which is  initially(最初的) zero and is updated by the appendReplacement method.

  A matcher may be reset  explicitly(明确的) by invoking its reset() method or, if a new input sequence is desired(需求), its reset(CharSequence) method. Resetting a matcher discards(废弃物) its  explicit(明确的) state information and sets the append position to zero.

  Instances of this class are not safe for use by multiple concurrent threads.