List outer=new ArrayList<String>();
    List inner=new ArrayList<String>();
    Connection con;
    Statement stmt;
    ResultSet rs;
    ResultSetMetaData rsmd;
    int columnNumber;
   try{
       Class.forName("com.mysql.jdbc.Driver");
       con=DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb","root","root");
       stmt=con.createStatement();
       rs=stmt.executeQuery("select * from mytable");
       rsmd=rs.getMetaData();
       columnNumber=rsmd.getColumnCount();
       while(rs.next()){
         for(int i=1;i<columnNumber;i++){
             inner.add(rs.getString(i));
         }
         outer.add(inner);
       }
       System.out.println("t" + outer);
       rs.close();
       con.close();
   }catch(Exception e){
        System.out.println(e);
   }