Android check if remote server is online

Question

I am new to Android programming and I have been facing problems that didn't exist in native Java. When I run this code in my computer, it runs correctly. But, when I run it in my device.I get nothing, I even tried to post the message to UI and there's no logcat for this. I am not sure what is wrong.

                try{
                    Socket socket = new Socket(serverAddr, SERVER_PORT);
                    Log.i("TAG","Socket connected");    
                }catch(IOException e){
                    Log.i("TAG","Socket not connected");
                }

Update 1: I just changed the code..nothing much and realized that after 2 minutes or so it does what it was supposed to do?? Is is anything to do with keep alive flags? Or is there anyway that I can run the code just for a second or two and stop it. Please understand that the code below the socket creation line executes only after 2 minutes if the server is dead. Here below is my code:

    try{
InetAddress serverAddr = InetAddress.getByName(serverIP);   
//Line below executes with no delay
postToUI("Trying to connect to standalone server" + "\n\n");
socket = new Socket(serverAddr, SERVER_PORT);
//Line below executes after 2 minutes
postToUI("Successfully connected to standalone server" + "\n\n");

}catch(ConnectException e){
    postToUI("Socket not connected");
}catch(IOException e){
    postToUI("Socket not connected");
}

I am not sure but you can try this: http://stackoverflow.com/questions/1443166/android-how-to-check-if-the-server-is-available — Dmytro Danylyk, Feb 04 '12 at 10:16
It talks about alive host. In which case even if the server application is not listening but, if server host is alive then it will be good. In my case i want to find out if my server is accepting connection. — Milan, Feb 04 '12 at 10:19
It looks like some error is thrown. Try looking for it in the logs or replace `IOException` with `Throwable`. — Piotr Praszmo, Feb 04 '12 at 12:24
If you are getting neither log message in LogCat, then you are not executing the code you have shown above. — CommonsWare, Feb 04 '12 at 12:35
@CommonsWare the code just before the try block is executing. — Milan, Feb 04 '12 at 12:51
Then one of those log messages will be in LogCat, or you will get a "force close" dialog due to an unhandled exception and that stack trace will be in LogCat. Particularly on the one in the `catch` block, please add the exception as a third parameter to the `i()` call, so you see the stack trace. — CommonsWare, Feb 04 '12 at 13:18
Like i said..i got exception just after couple of minutes...i am not sure...what is wrong — Milan, Feb 04 '12 at 20:53

score 0 · Answer 1 · answered Jul 23 '12 at 17:29

I have done very few Andrioid development so don't bite me smiley.

Possible reasons why the host might not communicate with the client

Host has firewall which might be closing the connection (unlikely)
Host might have unexpectly shutdown e.g power failure (unlikely)
Host might not properly port forwared (possibly)
Your andriod app doesn't have the proper manifest that allows the use of sockets.
Your andrioid device you are testing on might have its internet disabled which can enabled easily.
Host's address could have changed if it is dynamic.

For logcat, I think that logcat only displays log messages for the main thread. But I am unsure.

Android check if remote server is online

1 Answers1