How to append the IP (dynamically) to the connection String?

Asked Jul 14 '14 at 06:50

Active Jul 14 '14 at 11:04

Viewed 86 times

I have an android app that connects to the MySQL through jdbc,I use connection string where I want to append the IP to it by detecting innetwork.

String url = "jdbc:mysql://"+host+":"+  port + "/" + dbname;

where port and dbname are hardcoded,where IP is retrieved by a method and stored in host variable.

I can able to print the connection string through Toast.maketext() and it displayes perfectly,but while connecting to db it shows a nullpointer exception.

asked Jul 14 '14 at 06:50

Sukan

Please provide more code – ntv1000 Jul 14 '14 at 06:52
Regarding which one ? Because I'm 100% sure that the string is perfectly displayed in the Toast. – Sukan Jul 14 '14 at 06:55
A NullPointerException means that you want to use something that has not been initialized. So my guess is that this has nothing to do with the connection string. – ntv1000 Jul 14 '14 at 06:58
sorry mate! I tried all possible solutions,its printing perfectly in the toast but not connecting to database. – Sukan Jul 14 '14 at 07:09
Please, provide connection routine code. – A.Vynohradov Jul 14 '14 at 07:16
connection routine ? which one ? – Sukan Jul 14 '14 at 07:21
Block that contains `Class.forName("com.mysql.jdbc.Driver");` and `DriverManager.getConnection();` statements. – A.Vynohradov Jul 14 '14 at 07:24
con=DriverManager.getConnection(url,"abc","abc") – Sukan Jul 14 '14 at 07:52
@user3819356 how to convert an IP to a string format? I guess the issue is there. – Sukan Jul 14 '14 at 07:53
Provide the whole block of code where you obtain IP, store it in the `host` variable and request connection to the DB. – A.Vynohradov Jul 14 '14 at 07:57
http://stackoverflow.com/questions/6064510/how-to-get-ip-address-of-the-device – Sukan Jul 14 '14 at 10:06
I followed the above link.I found out that it retrieves the Gateway no the IPv4 address. – Sukan Jul 14 '14 at 10:06
Use an IDE and set appropriate breakpoints to determine what variable is null. Also, the stacktrace of the exception should tell you exactly what line it is on – DeathByTensors Jul 14 '14 at 11:32

How to append the IP (dynamically) to the connection String?

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