Question

Ok here’s my doubt…

I have a blazeDS (tomcat) application with some classes, each Class use the Config and DB Class for configuration and DB connection…

Here’s an example of

ConfigClass

public class Config {
    public static final String DBClass = "oracle.jdbc.driver.OracleDriver";
    public static final String ConnectString = "jdbc:oracle:thin:@//127.0.0.1:1521/xe";
    public static final String UserDB = "user";
    public static final String PasswordDB = "pass"; 
}

DB Class

public class DB
{       
    public DB() {}

    public static Connection dbConnect(Connection c)
    {
                try
                {      if (c == null || c.isClosed()){                                  
                            Class.forName(Config.DBClass);
                            c = DriverManager.getConnection(Config.ConnectString,Config.UserDB,Config.PasswordDB);
                        }
                return c;                        
                }
                catch (Exception e)
                {
                        System.out.println(e.getMessage());
                        return null;
                }
    }

    public static void closeConnection(Connection connection) throws SQLException
    {
        if (!connection.isClosed())
            connection.close();
    }
}

I have a test and production environment, with different user/password per DB access..
I noticed that when updating the production file with the test classes (I do not overwrite the Config.class), I got error from DB…

So, are the static final values (user/pass) in compiled version saved directly in the class itself (in my case DB.class)???

Answer 1

In short, yes.

An excerpt from the Java specs:

“References
to fields that are constant variables (§4.12.4) are resolved at
compile-time to the constant value that is denoted. No reference to
such a field should be present in the code in a binary file (except in
the class or interface containing the field, which will have code to
initialize it). Such a field must always appear to have been
initialized (§12.4.2); the default initial value for the type of such
a field must never be observed. See §13.4.9 for a discussion.” (p.
339)