Java: Replace a string from multiple replaced strings to multiple substitutes

Provide helper methods to replace a string from multiple replaced strings to multiple substitutes

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


public class StringHelper {
	
	/**
	 * This is test method to replace a string from:
	 * aaa > zzz
	 * 	 > /t
	 * 
 > /r
	 * 
 > /n
	 */
	public static void run()
	{
		
		String[] replacedStrings = new String[] {"aaa", "	", "
", "
"};
		String[] replacements = new String[] {"zzz", "/t", "/r", "/n"};
	
		Pattern pattern = getReplacePattern(replacedStrings);
		
		// The result is "zzza/tb/rc/nd/te/nf"
		System.out.println(replace("aaaa	b
c
d	e
f", pattern, replacedStrings, replacements));
		
		// The result is "zzza/tb/rc/nd/te/nf/r"
		System.out.println(replace("aaaa	b
c
d	e
f
", pattern, replacedStrings, replacements));
	}
	
	/**
	 * Return a Pattern instance from a specific replaced string array.
	 * @param replacedStrings replaced strings
	 * @return a Pattern instance
	 */
	public static Pattern getReplacePattern(String[] replacedStrings)
	{
		if (replacedStrings == null || replacedStrings.length == 0) return null;
		
		String regex = "";
		for (String replacedString : replacedStrings)
		{
			if (regex.length() != 0)
			{
				regex = regex + "|";
			}
			regex = regex + "(" + replacedString + ")";
		}
		regex = regex + "";

		return Pattern.compile(regex, Pattern.DOTALL | Pattern.MULTILINE);
	}
	

	/**
	 * Replace a string.
	 * @param value the string.
	 * @param pattern the Pattern instance.
	 * @param replacedStrings the replaced string array.
	 * @param replacements the replacement array.
	 * @return
	 */
	public static String replace(String value, Pattern pattern, String[] replacedStrings, String[] replacements)
	{
		if (pattern == null) return value;
		if (replacedStrings == null || replacedStrings.length == 0) return value;
		if (replacements == null || replacements.length == 0) return value;
		
		if (replacedStrings.length != replacements.length) 
		{
			throw new RuntimeException("replacedStrings length must same as replacements length.");
		}
		
		Matcher matcher = pattern.matcher(value);
		StringBuffer buffer = new StringBuffer();
		int lastIndex = 0;
		
		while (matcher.find()) {
			buffer.append(value.subSequence(lastIndex,  matcher.start()));
			lastIndex = matcher.end();

			String group = matcher.group();
			 
			for (int i = 0; i < replacedStrings.length; i++)
			{
				if (group.equals(replacedStrings[i]))
				{
					buffer.append(replacements[i]);
					break;
				}
			}
	     }
		 
		 buffer.append(value.subSequence(lastIndex, value.length()));
		 return buffer.toString();
	}
}