How do I pass a string parameter stored in the variable to the sql statement?

[phpuser123]

How do I insert a string that is stored in a variable into an sql statement?

 
void InsertVehicle(double vehicle_locX,double vehicle_locY,int vehicle_TAID,double vehicle_Gpsid,double vehicle_speed,String vehicle_type,int vehicle_routeid,String vehicle_status,int vehicle_passengerno,int vehicle_capacity) throws SQLException{
                    PreparedStatement preparedstatement=null;
                    ResultSet resultset=null;
                    String route_table;
 
                    if (conn!=null){
 
                            String sql="Insert into tbl_vehicle(vehicle_locX,vehicle_locY,vehicle_TAID,vehicle_Gpsid,vehicle_speed,vehicle_type,vehicle_routeid,vehicle_status,vehicle_passengerno,vehicle_capacity) Values("+vehicle_locX+","+vehicle_locY+","+vehicle_TAID+","+vehicle_Gpsid+","+vehicle_speed+","+'vehicle_type'+","+vehicle_routeid+","+vehicle_status+","+vehicle_passengerno+","+vehicle_capacity+")";
                            preparedstatement=conn.prepareStatement(sql);
                            preparedstatement.executeQuery();
 
                           }
                    }
 

Here I have vehicle_type which is of type string and while inserting it in my table 'vehicle_type' is stored instead of the value it contains.How do I sort this out?