>>590
API ドキュメント見ればこれくらい書けるでしょ…かなり適当だが

public static void main(String[] args) {
HashMap<String, String> map = new HashMap<String, String>();
map.put("1", "一");
map.put("7", "七");
map.put("26", "二十六");

String str = "あい(id:1)うえおか(id:7)きくけこさ(id:26)しすせそ";
Pattern p = Pattern.compile("\\(id:(\\d+)\\)");
Matcher m = p.matcher(str);
StringBuffer sb = new StringBuffer();
while(m.find()) m.appendReplacement(sb, map.get(m.group(1)));
m.appendTail(sb);
System.out.println(sb.toString());
}

http://java.sun.com/j2se/1.5.0/ja/docs/ja/api/java/util/regex/Pattern.html
http://java.sun.com/j2se/1.5.0/ja/docs/ja/api/java/util/regex/Matcher.html#appendReplacement(java.lang.StringBuffer, java.lang.String)