Android-如何将数据从主要活动发送到加载的片段

Question

I want to have a function that is constant between all my Fragments placed in MainActivity . I am not sure how to pass the data to the active Fragment since the Fragment will be unaware of the function being run.

I have tried creating an interface in the MainActivity and have the Fragment implement the MainActivity.OnDataPass . but not sure how to initiate the interface in the MainActivity I keep getting a NullPointerException .

In my main activity:

public class Mainactivity extends FragmentActivity{
    OnDataPass dataPasser;
    BroadcastReceiver receiver;
    @Override 
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        receiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String str = intent.getStringExtra("data");
                dataPasser.onDataPass(str);
            }
        };
    }

    public interface OnDataPass {
        public void onDataPass(String data);
    }
}

In my Fragment

public class Storage extends Fragment implements Mainactivity.OnDataPass{
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        mrootview = (ViewGroup) inflater.inflate(R.layout.storage, container, false);
        return mrootview;
    }

    @Override
    public void onDataPass(String data) {
        Log.v(TAG, data);

    }
}

am I even on the right track or is there a better way to send data to the fragment?

Answer 1

You are pretty far already:

public class Mainactivity extends FragmentActivity{
    OnDataPass dataPasser;

    @Override 
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //When you create your fragment, keep a reference of it in the dataPasser variable
        dataPasser = /* your storage fragment class or any other fragment that implements onDataPass*/
        ......
        receiver = new BroadcastReceiver() {
              @Override
               public void onReceive(Context context, Intent intent) {
                    String str = intent.getStringExtra("data");
                    dataPasser.onDataPass(str);
               }
        };
    }       


    public interface OnDataPass {
        public void onDataPass(String data);
    }
}