gMale Another

The code above from Alan Moore has two problems:
1) it doesn't take advantage of appendReplacement properly
2) it doesn't account for null pointers or unmatched properties

Here is a slight tweak to the code that resolves those issues:public String replaceVariables(String input, Map<String, String> context) { if(context == null || input == null) return input; Matcher m = Pattern.compile( "\\$\\{([^}]*)\\}" ).matcher( input ); // Have to use a StringBuffer here because the matcher API doesn't accept a StringBuilder -kg StringBuffer sb = new StringBuffer(); while(m.find()) { String value = context.get(m.group(1)); if(value != null) m.appendReplacement(sb, value); } m.appendTail(sb); return sb.toString(); }Of course, nowadays, there are plenty of frameworks that handle this kind of thing for us like Spring's PropertyPlaceholderHelper.