Re: Closing Database Connection

Lew <>
Tue, 15 Dec 2009 14:19:31 -0800 (PST)
Jerim wrote:

I have an all purpose Database Class.
There are two methods in this class: DBConnect() and DBClose().

package Program;

Package names should be all lower case.

import java.sql.*;

public class Database{

    public void DBConnect(){

Method names should begin with a lower-case letter. Type names begin
with upper case, so this method looks confusingly like a constructor.

    Connection conn = null;

You never expose this result outside the method. Perhaps the method
could return the connection instead of void, or you could set an
instance variable.

There are ways to avoid the superfluous assignment to null. You don't
need it at all in the local variable, and it's automatic for instance

               String userName = "root";
               String password = "passwor";
               String url = "jdbc:mysql://localhost/pro=


               Class.forName ("com.mysql.jdbc.Driver").ne=

wInstance ();

Why are you instantiating the driver class? It accomplishes nothing;
you aren't using the instance.

               conn = DriverManager.getConnection (url,=


               System.out.println ("Database connection e=


Use logging frameworks instead of System.out. Consider whether such
events even need to be logged.

           catch (Exception e)

Catching non-specific exceptions is (usually) an antipattern. Better
to catch 'SQLException'.

               System.err.println ("Cannot connect to dat=



You aren't handling the exception, only reporting it. This block
needs code to handle the exception, e.g., abort the method or provide
an alternative return or rethrow a wrapping exception..



    public void DBClose(String conn){

If you decide to make 'conn' an instance variable, you won't need it
as an argument.

                       conn.close ();
                       System.out.println ("Datab=

ase connection

                   catch (Exception e) { /* ignore cl=

ose errors */ }



I can connect to the database just fine. My question, is that when
calling the DBClose() method, how do I pass along the connection I

Return 'conn' from the 'DBConnect()' [sic] routine and assign it to a
variable in the calling routine, or store it in an instance variable
in the 'Database' class.

created when I called DBConnect()? I have a sample program setup that
opens the database connection and then tries to close it.

package Program;

public class Processing {
    public void Login(String Username, String Password){

Both method names and variable names (if not static constants) should
begine with lower-case letters. Your variables look like type names

Word parts within the names should be individually capitalized, a form
known as "camel case". Thus, in:

        Database dbconnection = new Database();

the variable name should be 'dbConnection'.

See the Java coding conventions document.

        //Database operations go here

'conn' would need to be declared in this scope.



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