Interrupt starting of an activity

This is probably a trivial question for experienced devs, but since I'm comming from PHP I'm struggling with the following problem:

I'm starting an activity. First thing it does ( in onCreate() ) is checking if a network connection is available. If not, I'm showing a dialog. So far it's working. However, in that case, I'd like to stop the startup-routine (onCreate, onResume, ...). How can I do that?

I've now changed my approach to putting e开发者_开发知识库verything in try/catch constructs, but many functions throw the same IOException error - how can I distinguish and show the appropriate message/dialog ? (eg: no wifi/3g available, no http connection possible, downloaded file is empty etc) ?

I've looked for tutorials but haven't found any that go more in detail but the obvious "try/catch" explanation...

Move code from onCreate() to separate method ex. init() . Test network connection in onCreate(), when passed invoke init(), if not - finish().

@Override
protected void onCreate(Bundle savedInstanceState) {
    if(isConnectionAvailable()){
        init();
    }else{
        Toast.makeText(this, "Not connected", Toast.LENGTH_SHORT).show();
        finish();
    }
}


public boolean isConnectionAvailable() {
    ConnectivityManager manager           = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo         activeNetworkInfo = manager.getActiveNetworkInfo();

    return (activeNetworkInfo != null) && activeNetworkInfo.isConnected();
}

It would be better to check this before you start your Activity or you can call finish() on your Activity if you don't have internet connection.

After checking connection , if you have not net connection ,then finish() 
your activity so it will stop further process automatically

For Checking all connection See my answer there