1、利用handler传递消息:

①子线程中发出消息,通知Handler完成UI更新:

new Thread(){
    @Override
    public void run() {

           //省略耗时操作,完成之后发送消息给Handler,完成UI更新;

           Message msg = Message.obtain(); 
           msg.what = SHOW_UPDATE_DIALOG;
           handler.sendMessage(msg);  
    }
}.start();

②handler方法:

private Handler handler = new Handler(){
        public void handleMessage(android.os.Message msg){
            switch(msg.what){
                case SHOW_UPDATE_DIALOG:
                    //提示用户更新
                    String desc = (String)msg.obj;
                    //更新UI
                    ll_loading.setVisibility(View.INVISIBLE);
                    break;
                default:
                    break;
            }
        }
};

2.直接在子线程中调用runOnUiThread更新UI

new Thread(){
    @Override
    public void run() {

           //省略耗时操作,完成之后发送消息给Handler,完成UI更新;

          runOnUiThread(new Runnable(){
                    @Override
                    public void run() {
                        ll_loading.setVisibility(View.INVISIBLE);
                    }
                });
    }
}.start();