public static void init(final Application app) {
        if (sApplication == null) {
            if (app == null) {
                sApplication = getApplicationByReflect();
            } else {
                sApplication = app;
            }
            sApplication.registerActivityLifecycleCallbacks(ACTIVITY_LIFECYCLE);
        } else {
            if (app != null && app.getClass() != sApplication.getClass()) {
                sApplication.unregisterActivityLifecycleCallbacks(ACTIVITY_LIFECYCLE);
                ACTIVITY_LIFECYCLE.mActivityList.clear();
                sApplication = app;
                sApplication.registerActivityLifecycleCallbacks(ACTIVITY_LIFECYCLE);
            }
        }
    }
Init utils.
<p>Init it in the class of Application.</p>

@param app application
imitate/src/main/java/com/engineer/imitate/util/Utils.java