我无法从任何类获得IntentService的任何值

Question

我正在尝试将值传递给IntentService类。但我无法从任何阶级中获得价值。

我这样跟着：

    public class ModelClass {

    private static ModelClass mInstance = null;
    Activity mActivity;
    String mString;

    public static ModelClass getInstance() {
        if (mInstance == null) {
            mInstance = new ModelClass();
        }
        return mInstance;
    }

    public String getmString() {
        return mString;
    }

    public void setmString(String mString) {
        this.mString = mString;
    }



    public void setmActivity(Activity activity){
        mActivity=activity;
    }

    public Activity getmActivity(){
        return mActivity;
    }
}

我正在设置类似HomePage的值。

public class Home extends Activity{
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    ModelClass.getInstance().setmActivity(this);
    ModelClass.getInstance().setmString("Testing String");
  }
}

我收到的价值如下： -

public class BackgroundService extends IntentService {
@Override
    public void onCreate() {
        // TODO Auto-generated method stub
        super.onCreate();
        System.out.println("On Create==> ");       
        System.out.println("getmString() ==> "+ModelClass.getInstance().getmString());
        System.out.println("getmActivity() ==> "+ModelClass.getInstance().getmActivity());

    }

}

但我在这里获得空值。如果我试图获取主页中的值意味着我可以查看值。请告诉我为什么我无法在IntentService中获得价值？