Matcher.appendReplacement example – Part 2

Byron KiourtzoglouNovember 11th, 2012Last Updated: August 13th, 2013

0 61 1 minute read

In this example we shall show you how to use Matcher.appendReplacement(StringBuffer sb, String replacement) API method to append to a StringBuffer the result of a Matcher. To use a StringBuffer to append a Matcher’s result one should perform the following steps:

Compile a given String regular expression to a Pattern, using compile(string regex) API method of Pattern.
Use matcher(CharSequence input) API method of Pattern to create a Matcher that will match the given String input against this pattern.
Create a new StringBuffer.
While the matcher finds the next subsequence of the input sequence that matches the pattern, with find() API method of Matcher get the input subsequence matched, with group() API method of Matcher and append it to the StringBuffer, implementing a non-terminal append-and-replace step, using appendReplacement(StringBuffer sb, String replacement) API method of Matcher.
Then use appendTail(StringBuffer sb) API method of Matcher to implement a terminal append-and-replace step and print the result from the StringBuffer,

as described in the code snippet below.

package com.javacodegeeks.snippets.core;

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

public class AppendRepl {

    public static void main(String[] argv) throws Exception {


  CharSequence input = "ab12 cd efg34 asdf 123";

  String pattStr = "([a-zA-Z]+[0-9]+)";


  Pattern p = Pattern.compile(pattStr);

  Matcher m = p.matcher(input);


  StringBuffer bufStr = new StringBuffer();

  

  boolean flag = false;

  

  while ((flag = m.find())) {


String rep = m.group();


m.appendReplacement(bufStr, "found<" + rep + ">");

  }

  m.appendTail(bufStr);


  String result = bufStr.toString();

  System.out.println(result);
    }
}

Output: