When to request permission at runtime for Android Marshmallow 6.0?

Question

I am testing my app on Marshmallow 6.0 and it's getting force closed for the android.permission.READ_EXTERNAL_STORAGE, even if it is defined in the Manifest already. Somewhere I have read that if I request permission at runtime then it would not force close your application. I have read this android document also, which is for requesting runtime permission.

So, I came to know that we can request a permission like below which is mentioned in the android document.

// Here, thisActivity is the current activity
if (ContextCompat.checkSelfPermission(thisActivity,
                Manifest.permission.READ_CONTACTS)
        != PackageManager.PERMISSION_GRANTED) {

    // Should we show an explanation?
    if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity,
            Manifest.permission.READ_CONTACTS)) {

        // Show an expanation to the user *asynchronously* -- don't block
        // this thread waiting for the user's response! After the user
        // sees the explanation, try again to request the permission.

    } else {

        // No explanation needed, we can request the permission.

        ActivityCompat.requestPermissions(thisActivity,
                new String[]{Manifest.permission.READ_CONTACTS},
                MY_PERMISSIONS_REQUEST_READ_CONTACTS);

        // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
        // app-defined int constant. The callback method gets the
        // result of the request.
    }
}

The above code has a callback method onRequestPermissionsResult which gets the result.

@Override
public void onRequestPermissionsResult(int requestCode,
        String permissions[], int[] grantResults) {
    switch (requestCode) {

     }
}

My question is where to exactly request the permission to user? Should we use the requesting permission at start of the app or should we do it as when the permission is required?

Answer 1

In general, request needed permissions it as soon as you need them. This way you can inform the user why you need the permission and handle permission denies much easier.

Think of scenarios where the user revokes the permission while your app runs: If you request it at startup and never check it later this could lead to unexpected behaviour or exceptions.