Answer by Hossain Ahamed for How do I fix 'android.os.NetworkOnMainThreadException'?

You can not call network on the main thread or UI thread. On Android if you want to call network there are two options -

1. Call asynctask, which will run one background thread to handle the network operation.
2. You can create your own runnable thread to handle the network operation.

Personally I prefer asynctask. For further information you can refer this link.