Matcher usePattern(Pattern) method in Java with Examples

The usePattern() method of Matcher Class is used to get the pattern to be matched by this matcher. Syntax:

public Matcher usePattern(Pattern newPattern)

Parameters: This method takes a parameter newPattern which is the new pattern to be set. Return Value: This method returns a Matcher with the new Pattern. Exception: This method throws IllegalArgumentException if newPattern is null. Below examples illustrate the Matcher.usePattern() method: Example 1:

Java

// Java code to illustrate usePattern() method

import java.util.regex.*;

public class GFG {
    public static void main(String[] args)
    {

        // Get the regex to be checked
        String regex = "Geeks";

        // Create a pattern from regex
        Pattern pattern
            = Pattern.compile(regex);

        // Get the String to be matched
        String stringToBeMatched
            = "GeeksForGeeks";

        // Create a matcher for the input String
        Matcher matcher
            = pattern
                  .matcher(stringToBeMatched);

        // Get the new Pattern
        String newPattern = "GFG";

        // Get the Pattern using pattern method
        System.out.println("Old Pattern: "
                           + matcher.pattern());

        // Set the newPattern using usePattern() method
        matcher = matcher
                      .usePattern(
                          Pattern
                              .compile(newPattern));

        // Get the Pattern
        // using pattern method
        System.out.println("New Pattern: "
                           + matcher.pattern());
    }
}

Output:

Old Pattern: Geeks
New Pattern: GFG

Example 2:

Java

// Java code to illustrate usePattern() method

import java.util.regex.*;

public class GFG {
    public static void main(String[] args)
    {

        // Get the regex to be checked
        String regex = "GFG";

        // Create a pattern from regex
        Pattern pattern
            = Pattern.compile(regex);

        // Get the String to be matched
        String stringToBeMatched
            = "GFGFGFGFGFGFGFGFGFG";

        // Create a matcher for the input String
        Matcher matcher
            = pattern
                  n.matcher(stringToBeMatched);

        // Get the new Pattern
        String newPattern = "Geeks";

        // Get the Pattern using pattern method
        System.out.println("Old Pattern: "
                           + matcher.pattern());

        // Set the newPattern using usePattern() method
        matcher = matcher
                      .usePattern(
                          Pattern
                              .compile(newPattern));

        // Get the Pattern
        // using pattern method
        System.out.println("New Pattern: "
                           + matcher.pattern());
    }
}

Output:

Old Pattern: GFG
New Pattern: Geeks

Reference: Oracle Doc