JAVA EE: How to replace the values in the text with new values using replace methods

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RegexDemo.java

import java.util.regex.Matcher;

import java.util.regex.Pattern;

/**
 * 
 * replaceAll() and replaceFirst():
 * 
 * The Matcher replaceAll() and replaceFirst() methods can be used to
 * replace parts of the string the Matcher is searching through.
 *
 */

public class RegexDemo

{

    public static void main(String[] args)

    {

        String text = "John peter about this, and John Doe writes about that,"

                + " and John Wayne writes about everything.";

        String regex = "(John)";

        Pattern pattern = Pattern.compile(regex);

        Matcher matcher = pattern.matcher(text);

        /*
         * The replaceAll() method replaces all matches of the regular
         * expression.
         */

        String replaceAll = matcher.replaceAll("Steve");

        System.out.println("replaceAll   = " + replaceAll);

        /*
         * The replaceFirst() only replaces the first match.
         */

        String replaceFirst = matcher.replaceFirst("Steve");

        System.out.println("replaceFirst = " + replaceFirst);

    }

}

Output

replaceAll   = Steve peter about this, and Steve Doe writes about that, and Steve Wayne writes about everything.

replaceFirst = Steve peter about this, and John Doe writes about that, and John Wayne writes about everything.