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What is a regex.Pattern class in Java?

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A regular expression is a defined pattern used for matching and manipulating strings. In Java, there is a built-in API for regular expressions:

java.util.regex package

This package has three classes:

A regular expression is not the property of one particular programming language; instead, it is supported by multiple languages.

Pattern class

The util.regex.Pattern is used for defining text patterns. Some commonly used methods are:

Methods	Description
`compile (String regex, int flags)`	It compiles the given expression into a pattern using the given flags. Flags are optional.
`flags()`	It returns the flags of the given expression.
`matcher(charSequence input)`	It creates the matcher that matches the input with the given expression.
`matches(String regex, CharSequence input)`	It compiles the regular expression and matches it against the input.
`pattern()`	It returns the regular expression from which the pattern is derived.
`split(CharSequence input)`	It splits the given pattern around the matches of the given input.
`toString()`	It returns the String of the given pattern.

// Pattern.matches() in Java 
import java.util.regex.Pattern; 
  
class Main 
{ 
    public static void main(String args[]) 
    { 
        // The following statement prints true because
        // "Ah*" matches "Ahhhhhhhh"
        System.out.println (Pattern.matches("Ah*", 
                                            "Ahhhhhhhhh")); 
        // The following statement prints false because
        // "Educative" matches "Educative Inc."
        System.out.println (Pattern.matches("Educative", 
                                            "Educative Inc")); 
    } 
}

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