Can't create handler inside thread that has not called Looper.prepare()

报错：Can't create handler inside thread that has not called Looper.prepare()

原因：Toast不能直接在子线程中调用显示

场景：在子线程中进行了数据操作，并且用handler发送刷新ui并打印Toast

原代码如下：

new Thread(new Runnable() {    public void run() {        try {            EMClient.getInstance().groupManager().addUsersToGroup(groupId, newmembers);                        Qiuutil.ShortToast("已经添加群成员");            listuser.get(position).put("1","1");            handler.sendEmptyMessageDelayed(2,500);                    } catch (Exception e) {            Qiuutil.ShortToast("添加失败");        }    }}).start();

报错之后加上Looper.prepare();Looper.loop();中包裹handler和Toast 就不会报错，代码如下：

new Thread(new Runnable() {    public void run() {        try {            EMClient.getInstance().groupManager().addUsersToGroup(groupId, newmembers);            Looper.prepare();            Qiuutil.ShortToast("已经添加群成员");            listuser.get(position).put("1","1");            handler.sendEmptyMessageDelayed(2,500);            Looper.loop();        } catch (Exception e) {            Qiuutil.ShortToast("添加失败");        }    }}).start();