@Override
    public String toString() {
        StringBuilder sb = new StringBuilder(); 
        sb.append(name).append("\t");
        for(String s:colnames){
            if(s == null || s.isEmpty()){
                sb.append("col").append("\t");
            }else{
                sb.append(s).append("\t");
            }
        }
        sb.append("\n");
        for(int i = 0; i < drow; i++){
            if(rownames[i] == null || rownames[i].isEmpty()){
                sb.append("row").append(i + 1).append("\t");
            }else{
                sb.append(rownames[i]).append("\t");
            }          
            for(int j = 0; j < dcol; j++){
                sb.append(data[i][j]).append("\t");
            }
            sb.append("\n");
        }
        return sb.toString();
    }