Android Speech Recognition with RecyclerView

Question

I'm using this project https://github.com/googlesamples/android-RecyclerView as reference to learn about RecyclerView, and implementing the answer by MLProgrammer-Cim here to handle onClick events.

In my CustomAdapter activity I'm trying to start a method speakNow(); which is in another activity MainActivity

public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {
private static final String TAG = "CustomAdapter";
...

public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
    ...
    public MyViewHolderClicks mListener;
    private Context context;
    MainActivity ma = new MainActivity();

//        FragmentTransaction ft =     ((FragmentActivity)context).getSupportFragmentManager().beginTransaction();
//        SampleActivityBase fragment = (SampleActivityBase)ft.findFragmentByTag("SampleActivityBase");


    public ViewHolder(View myv, MyViewHolderClicks listener) {

        super(myv);
        mListener = listener;
        ....
        imageIcon.setOnClickListener(this);
        myv.setOnClickListener(this);
        this.context =context;


    }
    @Override
    public void onClick(View v) {
       int position = getLayoutPosition();
        if (v instanceof Button){
            mListener.onTomato((Button) v, getLayoutPosition());
            switch (v.getId()) {

               case R.id.button_for_cardview:
                   ma.speakNow();
 .....
 }
}

My MainActivity

public class MainActivity extends SampleActivityBase {
....
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
     ....
    //Intent intent = new Intent(getApplicationContext(),     CustomAdapter.class);
    //startActivityForResult(new Intent(this, CustomAdapter.class), checka);
    if (savedInstanceState == null) {
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        RecyclerViewFragment fragment = new RecyclerViewFragment();
        transaction.replace(R.id.sample_content_fragment, fragment);
        transaction.commit();
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {

  if (requestCode == checka && resultCode == RESULT_OK){
        ArrayList<String> results = data.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
        lv.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, results));

       .....
        }

    }
    super.onActivityResult(requestCode, resultCode, data);


}

protected void speakNow() {
    Intent a = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
    a.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
    a.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS, 6);
    a.putExtra(RecognizerIntent.EXTRA_PROMPT, GlobalVariables.getInstance().getRightAnswer1());
    startActivityForResult(a, checka);
}
....

}

This return a NullPointerException in MainActivity.speakNow(MainActivity.java:478) which is this startActivityForResult(a, checka); and Adapter$ViewHolder.onClick(CustomAdapter.java:287) which is ma.speakNow();

I've read various "calling Methods from other activities returning NPE", questions and answers,not too sure how those apply to my case since MainActivity extends SampleActivityBase which is a public abstract class which extends FragmentActivity.

Where / how do I need to intialize the MainActivity ma = new MainActivity(); so its not null? Thanks

Answer 1

the exception is thrown in startActivityForResult, that is because the Activity you create by MainActivity ma = new MainActivity(); is different from the Activity create by system, the Activity you created has nothing in it, read the source code of Activity to execute startActivityForResult , it depends on some member variable.so you got the nullpoint exception. you can add a setter in you adapter, pass the reference of Activity to adapter

public void setActivity(Activity aty) {
    this.aty = aty;
}