use [\\W+]
or "[^a-zA-Z0-9]"
as regex to match any special characters and also use String.replaceAll(regex, String) to replace the spl charecter with an empty string. remember as the first arg of String.replaceAll is a regex you have to escape it with a backslash to treat em as a literal charcter.
String c= "hjdg$h&jk8^i0ssh6";
Pattern pt = Pattern.compile("[^a-zA-Z0-9]");
Matcher match= pt.matcher(c);
while(match.find())
{
String s= match.group();
c=c.replaceAll("\\"+s, "");
}
System.out.println(c);