How Do We Distinguish Never-Asked From Stop-Asking in Android M's Runtime Permissions?

Question

When it comes to the M Developer Preview runtime permissions, according to Google:

1. If you have never asked for a certain permission before, just ask for it<

Answer 1

There is no need to create a parallel persistent state for the permission state, you could just use this method which returns the current permission state at any time:

@Retention(RetentionPolicy.SOURCE)
    @IntDef({GRANTED, DENIED, BLOCKED})
    public @interface PermissionStatus {}

    public static final int GRANTED = 0;
    public static final int DENIED = 1;
    public static final int BLOCKED = 2;

    @PermissionStatus 
    public static int getPermissionStatus(Activity activity, String androidPermissionName) {
        if(ContextCompat.checkSelfPermission(activity, androidPermissionName) != PackageManager.PERMISSION_GRANTED) {
            if(!ActivityCompat.shouldShowRequestPermissionRationale(activity, androidPermissionName)){
                return BLOCKED;
            }
            return DENIED;
        }
        return GRANTED;
    }

Caveat: returns BLOCKED the first app start, before the user accepted/denied the permission through the user prompt (on sdk 23+ devices)

I also used this answered here.