activity.runOnUiThread（）內的run（）方法沒有被執行

activity.runOnUiThread(new Runnable() {
                public void run()
                {
                    Toast.makeText(context, toast, Toast.LENGTH_SHORT).show();
                }
            });

run（）方法沒有執行，查找緣由，在原來，掉用runOnUiThread的activity，必定得是Activity對象，so，在使用以前，須要增長判讀：

if（activity instanceOf Activity）{

}

參考連接 

原文：

It doesn't always work, you have to be sure that what you are casting is
 effectively an Activity or you'll have a ClassCastException. To do that you can do "if(context instanceOf Activity){ // proceed to cast }"