private boolean validateChange(StringBuffer newVal, int mode, int limit, 
                                   int scale) {
        
        if(mode == NUMERIC || mode == INTEGER){
            String n = newVal.toString();
            if(n!=null && !n.isEmpty()){
                if(n.startsWith("+") || n.startsWith("-")){
                    newVal = new StringBuffer(n.substring(1, n.length()-1));
                }
            }
        }