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Java in a Nutshell, 5th Edition by David Flanagan

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Name

Pattern

Synopsis

This class represents a regular expression. It has no public constructor: obtain a Pattern by calling one of the static compile( ) methods, passing the string representation of the regular expression, and an optional bitmask of flags that modify the behavior of the regex. pattern( ) and flags( ) return the string form of the regular expression and the bitmask that were passed to compile( ).

If you want to perform only a single match operation with a regular expression, and don't need to use any of the flags, you don't have to create a Pattern object: simply pass the string representation of the pattern and the CharSequence to be matched to the static matches( ) method: the method returns true if the specified pattern matches the complete specified text, or returns false otherwise.

Pattern represents a regular expression, but does not actually define any primitive methods for matching regular expressions to text. To do that, you must create a Matcher object that encapsulates a pattern and the text it is to be compared with. Do this by calling the matcher( ) method and specifying the CharSequence you want to match against. See Matcher for a description of what you can do with it.

The split( ) methods are the exception to the rule that you must obtain a Matcher in order to be able to do anything with a Pattern (although they create and use a Matcher internally). They take a CharSequence as input, and split it into substrings, using text that matches the regular expression ...

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