Jose Vives

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since Apr 18, 2015
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Recent posts by Jose Vives

Hi. I'm trying draw on a panel inside a frame. But all the time I get 2Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException" in the repaintComponent.
This is all the exception error.



and keeps repeating all the time.

the code is the below



I'm trying to implement the langton's ant problem on java. Inside ant.render(g) is jus the follow code


My idea is on repaintcomponent paint the world an the ant positions. But I can't get this work. Any solution? thanks!
8 years ago
At the moment I have all the querys working in one file for two tables, but now I want add another two tables to the database, and I need write all de methods for get information and do all the operations I want. But all in the same class is a bit messy. So I want to create a new class for each table and put all the methods related with that class. But I already have all the sql code working
8 years ago
Hi. I have a generic question and I don't understand how create what I want.
I writing a basic program they can access to one database an do some SQL request, etc. But at the moment I have one big class with all SQL for all the tables from the database. And I want slipt this class in different classes for make the code more easy to read and implement stuff. I think the best solution is create one subclass for each table on the database and on for this class put all the methods related on this class. But later I don't understand how I can call this methods from the class. Because for access to the database I create an object DataBase on the main application and if I want call a method just I do a database.methodIWant().
At the moment I have:

DataBase (this class have all the methods for the databases) extends DataBaseUtil
DataBaseUtil (this class contain all methods and information for connect to the database)

and I crate the database object wit "DataBase db = new DataBase();

And I want something like:


DataBase (this class have all the methods for the databases) extends DataBaseUtil
DataBaseUtil (this class contain all methods and information for connect to the database)
and classes for example:
DogSQL (all the methods for the table dog on the database)
CatSQL (all the methods for the table cat on the database)

and I create the database object wit "DataBase db = new DataBase(); and call methods like db.methodFromDogSQL();

I don't understand how do this. Im starting and my knowledge in java is a bit basic, so I want learn how do this type of stuff. Thanks
8 years ago