How to connect one database in two threads?

Question

Dear All,
If anyone can tell me how to connect one database concurrently?
I tried the following idea:
1.create a Hashtable to keep database objects(those databases have been opened)
2.Before openning(connecting) a database:first step is to check the hashtable.
If the the database object is in the hashtable, this object will be returned.
If the datatbase object is not in the hastable, open the database and store this opened database object into the hashtable.
I failed the test of this implementation. My test is:Create two threads (extend java Thread class).In each of these two threads, try to open the same database.Just like the following:
MyThread thread1 = new MyThread();
MyThread thread2 = new MyThread();
thread1.start();
thread2.start();
I guessed the database object in the hashtable would be returned in the second thread.Unfortunatly, I only got an exception which meant the database couldn't be opened twice.It looks like the second thread happened before the opened database object stored into the hashtable.
I cannot figure out if my design is wrong or my test application is wrong.
I really appriatiate your attentions!!!
Lu

Answer 1

um not sure i follow exactly but in your code add the word synchronise to it and this means only 1 tread can access it at any 1 time.
So your could have a class which is a singleton so it only opens the dbase once and then all other access share your connection.
so
public class foo{
foo INSTANCE = new foo();
private foo(){} //private constructor
then all your methods use foo's internal dbase connection. Am i making sense