Android:intent.getExtras().getSerializable(Constants.codiceMainActivity)为null [英] Android: intent.getExtras().getSerializable(Constants.codiceMainActivity) is null

问题描述

我想从我的主要活动中启动服务，并通过Serializable传递一个对象.但是，当我在Service中获取对象并调用方法时，该对象为null，我不知道为什么. 这是我的MainActivity类:

I want to start a service from my main activity and pass an object with Serializable. However when I get the object in the Service and I call a method, it is null and I don't know why. Here is my MainActivity class:

public class MainActivity extends AppCompatActivity implements View.OnClickListener, Serializable
{
private transient SetVocabulary setVocabulary;
private transient Intent intent;
@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    setVocabulary = new SetVocabulary();
    findViewById(R.id.imageDizionario).setOnClickListener(this);
    findViewById(R.id.imageGruppi).setOnClickListener(this);
    findViewById(R.id.imageImpara).setOnClickListener(this);

    Intent intentService = new Intent(MainActivity.this, ServiceChiusuraApp.class);
    intentService.putExtra(Constants.codiceMainActivity,this);
    Bundle bundleService = new Bundle();
    bundleService.putSerializable(Constants.codiceMainActivity,this);
    intentService.putExtras(bundleService);
    startService(intentService);
}

public SetVocabulary getSetVocabulary()
{
    return setVocabulary;
}

@Override
public void onClick(View v)
{
    startActivity(intent);
}

}

这是我的服务班级:

public class ServiceChiusuraApp extends Service
{
MainActivity mainActivity;
@Override
public IBinder onBind(Intent intent)
{
    mainActivity = (MainActivity) intent.getExtras().getSerializable(Constants.codiceMainActivity);
    return null;
}

@Override
public void onTaskRemoved(Intent rootIntent)
{
    super.onTaskRemoved(rootIntent);
    SharedPreferences sharedPref = mainActivity.getPreferences(Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPref.edit();
    editor.putStringSet(Constants.codiceSetString,mainActivity.getSetVocabulary());
    stopSelf();
}
}

推荐答案

您想将数据从Service返回到Activity.有几种方法可以做到这一点:

You want to return data from your Service to your Activity. There are several ways to do this:

• 将Activity绑定到Service，并使用AIDL在Service上创建一个返回数据的方法.
• 在Activity中创建一个BroadcastReceiver，以侦听特定的Intent ACTION.在您的Service中，当您要将数据发送到Activity时，使用适当的ACTION创建一个Intent，将数据添加为"extras"，然后调用sendBroadcast().

• Bind your Activity to your Service and using AIDL create a method on your Service that returns data.
• Create a BroadcastReceiver in your Activity that listens for a specific Intent ACTION. In your Service, when you want to send data to the Activity,create an Intent with the appropriate ACTION, add the data as "extras", and call sendBroadcast().

这篇关于Android:intent.getExtras().getSerializable(Constants.codiceMainActivity)为null的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！