Java Application for a website

[r-senior]

I think you may misunderstand the concept of a data access object (DAO).

https://en.wikipedia.org/wiki/Data_access_object
http://www.oracle.com/technetwork/ja...ct-138824.html

A recipe DAO will find recipes, create recipes, delete recipes and so on. The class you have creates connections so is more of a connection factory than a data access object.

I don't think you have the pieces set out in your mind and how they will fit together. You need to work on that.

Your compilation errors are because:

a. You are mixing a class definition with a method definition. You should have something more like:

public class ConnectionFactory {

	public Connection getConnection() throws SQLException {
            ...

b. You are referring to members of the class that don't exist: userName, password and dbms

But ... rather than just putting your head down and coding, you need to have a clear picture of how your main components fit together. That was the original question: how to split your application up into manageable components ... but I don't think you have the answer in your head.

Looking back at the thread, the main components appear to be:

1. Your main program
2. Something that manages connections (ConnectionFactory?)
3. Something that manages recipes (RecipeDAO?)

As an exercise, you could consider writing Hello World using two collaborating classes:

Hello.java

public class Hello {

    ...

}

MessageProvider.java

public class MessageProvider {

    public String getMessage() {
        return "Hello World";
    }

}

If you can do that and understand it, it's a step forward to reorganising your real application.

[TheodoreP]

Yes, I realize that I probably need to think my application through a little more clearly, but the thing is that I program to relieve stress and mellow out. After a long hard day of work, and little before work, I need to relax and this is one way of coping. Especially since I feel like and my parents agree that my employer is seriously screwing me out of every possible promotion that is opening up. Three times now I've been passed over. Enough of the ranting though, How might I call the getConnection() method from the ConnectionFactory file in the power file? I'm I correct in assuming that it might look somewhat like this:

connectionfactory.getConnection();

I'm currently calling the dao and connectionfactory files with the following code:

    // call to the database ConnectionFactory
    private ConnectionFactory connectionfactory;
    // call to the database access objects
    private RecipeDAO recipeDAO;
    private CommentsDAO commentsDAO;
    private UsersDAO usersDAO;

[r-senior]

When you program for pleasure, you have the freedom to create a piece of programming art that you can admire and be proud of.

This is looking good (it's so good, you don't even need the comments):

connectionfactory.getConnection();

    // call to the database ConnectionFactory
    private ConnectionFactory connectionfactory;
    // call to the database access objects
    private RecipeDAO recipeDAO;
    private CommentsDAO commentsDAO;
    private UsersDAO usersDAO;

[TheodoreP]

Need some help with my viewallrecipes method, I'm trying to create a way to display a list of all the recipes within the database so that I can ensure my connecionfactory is truly working it's wonderful magic and I'm having a little trouble calling the method in the power file as well as the printsqlexception at the end of the viewallrecipes method in the recipesdao file, However that can wait a little bit right now.

the following is the code used to call the viewallrecipes method in the power file

    private void makeCentralRegion() throws SQLException
    {
        Connection con = null;
        recipeDAO.viewAllRecipes(con, "sociable_recipe");
    }

and here is the viewallrecipes method code

    public void viewAllRecipes(Connection con, String dbname) throws SQLException {
        Statement stmt = null;
        String query = "select recipeid, title, poster, shortdesc from recipes";
        try {
            stmt = con.createStatement();
            ResultSet rs = stmt.executeQuery(query);
            while(rs.next()) {
                int recipeid = rs.getInt("recipeid");
                String title = rs.getString("title");
                String poster = rs.getString("poster");
                String shortdesc = rs.getString("shortdesc");
                System.out.println(recipeid + "/t" + title + "/t" + "posted by: Chef" + poster + "/t" + shortdesc);
            }
        } catch(SQLException e){
            power.printSQLException(e);
        } finally {
            if(stmt != null) { stmt.close(); }
        }
    }

My main issue is that I can't seem to understand how and what arguments to place in the parentheses.

[r-senior]

I wasn't sure which parentheses you meant.

At this stage, your DAO should look more like:

public class RecipeDAO {

    private Connection connection;

    public RecipeDAO(Connection connection) {
        this.connection = connection;
    }

    public List<Recipe> findAllRecipes() throws SQLException {
        Statement s = null;
        List<Recipe> recipes = new ArrayList<Recipe>();
        try {
            s = this.connection.createStatement();
            ...
            // Run your query, iterate over the results and add recipes to the list
            ...
            return recipes;
        }
        finally {
            // Close statement and resultset (but not the connection)
            ...
        }
    }

}

You don't want to catch the exception because you aren't doing anything useful with it. For now, let's just declare that you throw it and let your main program deal with it.

In your main program, you'll get your connection from your connection factory and create the DAO:

private void connectToDatabase() throws SQLException {
    ConnectionFactory factory = new ConnectionFactory();
    this.connection = connectionFactory.getConnection();
    this.recipeDAO = new RecipeDAO(connection);
    ...
}

When you want a list of recipes, you call the DAO:

List<Recipe> recipes = recipeDAO.findAllRecipes();
for (Recipe recipe : recipes) {
    // Do something with each recipe, e.g. add to the model for a Swing table
}

I'm assuming you understand the basics of using generics (the things in the <> brackets). If not, please say so.

[TheodoreP]

I'm assuming you understand the basics of using generics (the things in the <> brackets). If not, please say so.

I never really learned about these generics your talking about in the online courses I took, so I must answer no to your assumption. Could you please give a good example of how to code a query and iterate it over and over until all the recipes in the database are displayed. I have column named recipeid that auto-increments with every new recipe. As well, I was wondering if you could give a good example of how too close a statement and a resultset? In the recipe dao file everything is looking good but eclipse is showing me that lines 12 and 14 have errors in them and the errors are the <Recipe> generics? It could be that I just haven't added my iterated query and resultset yet but I don't know.

[1clue]

Never mind, replied to something on the first page which no longer is pertinent.

[ofnuts]

Could you please give a good example of how to code a query and iterate it over and over until all the recipes in the database are displayed.

This is normally something you avoid. Whats is costly in DB interaction is the request. Unless you are handling tens of megabytes of data or making very complex queries, you get much better performance by getting all your data in one query.

[r-senior]

I never really learned about these generics your talking about in the online courses I took, so I must answer no to your assumption.

Generics do many things, but of relevance here is that the finder methods, e.g. findAllRecipes return a list of recipes, which is defined as a return type of List<Recipe>. The generic part defines the type of object in the list. This makes it easy to iterate over:

Main Program

List<Recipe> recipes = recipeDAO.findAllRecipes();
for (Recipe recipe : recipes) {
   // Do something with each recipe
}

Could you please give a good example of how to code a query and iterate it over and over until all the recipes in the database are displayed.

If I did that, I'd have written the whole method. So I'll let you do that part.

I have column named recipeid that auto-increments with every new recipe.

You can define your primary key column as auto-increment. When you insert a recipe, don't set the primary key and the database will handle it.

https://dev.mysql.com/doc/refman/5.5...increment.html

This is normally something you avoid. Whats is costly in DB interaction is the request. Unless you are handling tens of megabytes of data or making very complex queries, you get much better performance by getting all your data in one query.

That's the way I read it. Then I read it a few more times and started to hope that it meant, "how to code a query and iterate over it".

[TheodoreP]

So, just to get a little hint of how to code the query and iterate it over and over until all recipes in the database are displayed I'll post some code and you can tell me if I'm close.

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.*;

public class RecipeDAO {
    private Connection connection;
    public RecipeDAO(Connection connection) {
        this.connection = connection;
    }
    public List<Recipe> findAllRecipes() throws SQLException {
        Statement s = null;
        List<Recipe> recipes = new ArrayList<Recipe>();
        s = this.connection.createStatement();
        // Run your query, iterate over the results and add recipes to the list
        String query = "select recipeid, title, poster, shortdesc from recipes";
        try {
            ResultSet rs = s.executeQuery(query);
            while(rs.next()) {
                int recipeid = rs.getInt("recipeid");
                String title = rs.getString("title");
                String poster = rs.getString("poster");
                String shortdesc = rs.getString("shortdesc");
                System.out.println(recipeid + "/t" + title + "/t" + "posted by: Chef" + poster + "/t" + shortdesc);
            }
            return recipes;        
        } finally {
            // Close statement and resultset (but not the connection)
                    if(s != null) { s.close(); }
        }
    }
}

So tell me, if I'm understanding how to query a database and iterate it over? If so, why is it telling me that the bolded generics are wrong or errors? As well, please let me know if I closed out the statement and resultset but, not the connection correctly?

As well in my power file in these lines:

    private void connectToDatabase() throws SQLException {
        ConnectionFactory factory = new ConnectionFactory();
        this.connection = ConnectionFactory.getConnection();
        this.recipeDAO = new RecipeDAO(connection);
    }

The bolded lines are recommending that I go to the getConnection() method and add a static type before the Connection type. Well, I tried it but I undid it because it then gives a whole bunch of errors in the getConnection() method and that means that it's wrong because keeping it how I have it now gives zero errors. Please help me with this if you could?