java.util.regex.Matcher.usePattern() Method

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Description

The java.util.regex.Matcher.usePattern(Pattern newPattern) method changes the Pattern that this Matcher uses to find matches with.

Declaration

Following is the declaration for java.util.regex.Matcher.usePattern(Pattern newPattern) method.

public Matcher usePattern(Pattern newPattern)

Parameters

• newPattern − The new pattern used by this matcher.

Return Value

this matcher.

Exceptions

• IllegalArgumentException − If newPattern is null.

Example

The following example shows the usage of java.util.regex.Matcher.usePattern(Pattern newPattern) method.

package com.tutorialspoint;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MatcherDemo {
   private static String REGEX = "(a*b)(foo)";
   private static String INPUT = "aabfooaabfooabfoob";

   public static void main(String[] args) {
      // create a pattern
      Pattern pattern = Pattern.compile(REGEX);
      
      // get a matcher object
      Matcher matcher = pattern.matcher(INPUT); 
      
      while(matcher.find()) {
         //Prints the start index of the subsequence captured by the given group.
         System.out.println("Second Capturing Group, (foo) Match String start(): "+matcher.start(1));
      }  
      matcher.reset();
      matcher.usePattern(Pattern.compile("(a*b)(foob)"));
      
      while(matcher.find()) {
         //Prints the start index of the subsequence captured by the given group.
         System.out.println("Second Capturing Group, (fooab) Match String start(): "+matcher.start(1));
      }  
   }
}

Let us compile and run the above program, this will produce the following result −

Second Capturing Group, (foo) Match String start(): 0
Second Capturing Group, (foo) Match String start(): 6
Second Capturing Group, (foo) Match String start(): 12
Second Capturing Group, (fooab) Match String start(): 12