更新UI，有时不成功是怎么回事

Question

我刚刚学习到通过Handler更新Android组件的事情，只是想要通过点击ImageView来在更新Fragment的同时让下方的Tab背景色有所改变。我想通过handle来更新的，代码如下：

public class administrator extends Activity {
    LinearLayout layout_monitoring;
    LinearLayout layout_message;
    LinearLayout layout_admin;
    LinearLayout layout_setting;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.administrator);
        ImageView image_monitoring=(ImageView) findViewById(R.id.image_monitoring);
        ImageView image_message=(ImageView) findViewById(R.id.image_message);
        ImageView image_admin=(ImageView) findViewById(R.id.image_admin);
        ImageView image_setting=(ImageView) findViewById(R.id.image_setting);
        layout_monitoring=(LinearLayout) findViewById(R.id.layout_monitoring);
        layout_message=(LinearLayout) findViewById(R.id.layout_message);
        layout_admin=(LinearLayout) findViewById(R.id.layout_admin);
        layout_setting=(LinearLayout) findViewById(R.id.layout_setting);
        image_monitoring.setOnClickListener(image_click);
        image_message.setOnClickListener(image_click);
        image_admin.setOnClickListener(image_click);
        image_setting.setOnClickListener(image_click);
        FragmentManager fragmentManager =getFragmentManager();
        FragmentTransaction ft =fragmentManager.beginTransaction();
        Fragment f=new administrator_monitoring_fragment();
        ft.replace(R.id.fragment,f);
        ft.commit();
    }
    Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.arg1)
            {
                case 1:
                {
                    layout_monitoring.setBackgroundResource(R.color.choose);
                    layout_message.setBackgroundResource(R.color.choose_not);
                    layout_admin.setBackgroundResource(R.color.choose_not);
                    layout_setting.setBackgroundResource(R.color.choose_not);
                }break;
                case 2:
                {
                    layout_monitoring.setBackgroundResource(R.color.choose_not);
                    layout_message.setBackgroundResource(R.color.choose);
                    layout_admin.setBackgroundResource(R.color.choose_not);
                    layout_setting.setBackgroundResource(R.color.choose_not);
                }break;
                case 3:
                {
                    layout_monitoring.setBackgroundResource(R.color.choose_not);
                    layout_message.setBackgroundResource(R.color.choose_not);
                    layout_admin.setBackgroundResource(R.color.choose);
                    layout_setting.setBackgroundResource(R.color.choose_not);
                }break;
                case 4:
                {
                    layout_monitoring.setBackgroundResource(R.color.choose_not);
                    layout_message.setBackgroundResource(R.color.choose_not);
                    layout_admin.setBackgroundResource(R.color.choose_not);
                    layout_setting.setBackgroundResource(R.color.choose);
                }break;
            }
            Message newMsg=new Message();
            newMsg.arg1=msg.arg1;
            msg=newMsg;
            handler.sendMessage(msg);
        }
    };
    View.OnClickListener image_click=new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            FragmentManager fragmentManager =getFragmentManager();
            FragmentTransaction ft =fragmentManager.beginTransaction();
            Fragment f=null;
            int choose_fragment=0;
            switch(v.getId())
            {
                case R.id.image_monitoring:
                    f=new administrator_monitoring_fragment();
                    choose_fragment=1;
                    break;
                case R.id.image_message:
                    f=new administrator_message_fragment();
                    choose_fragment=2;
                    break;
                case R.id.image_admin:
                    f=new administrator_admin_fragment();
                    choose_fragment=3;
                    break;
                case R.id.image_setting:
                    f=new administrator_setting_fragment();
                    choose_fragment=4;
                    break;
                default:
                    choose_fragment=0;
                    break;
            }
            Message msg=handler.obtainMessage();
            msg.arg1=choose_fragment;
            handler.sendMessage(msg);
            ft.replace(R.id.fragment,f);
            ft.commit();
        }
    };
}

但是我在APP里发现有的时候会更新失败，只是更新了fragment并没有改变tab的背景色。

难道是操作耗时所以导致message还没有来得及做完就以为受到新的message而中途失败了？