Balance Test Using Stack

public static boolean testBalance(String s) {
   charStack stk = new charStack();
   boolean okay = true;
   for (int i=0; okay && (i < s.length()); i++)
    {  char c = s.charAt(i);
       switch ( c ) {
       case '(': case '{': case '[':
           stk.push(c);
           break;
       case ')':
           if ( stk.empty() ||
                ( stk.pop() != '(' ) )
               okay = false;
           break;
       // same for '}' and ']'
       default: break;   // accept other chars
       } }
       return (okay && stk.empty() ); }