Help with regex

i need a help in regular exp, iam trying to find if two strings have all,some or not at all, common letters, if some of the letters are same, create as a new string, eg, str1="acyq" and str2="zyapkf"; i tried this but not getting neaar what i wanted, can someone give me examples even in other way to solve.

public String findSimilarity(String str){

String regvar=null;

String reg="[tap3]+";

Pattern pattern = Pattern.compile(reg);

Matcher matcher = pattern.matcher(str);

while(matcher.find()){

regvar =matcher.group();

}

return regvar;

}

[867 byte] By [fashrmrka] at [2007-10-3 11:33:39]