Error when I try to send variables with Intent - NullPointerException

Question

I'm trying to send an ArrayList<Pet> from a Fragment to MainActivity.java and from here, if you press an ImageButton(from the actionbar) it goes to another activity, in which I need the data from ArrayList. Well, I create an Intent in my Fragmentclass and a Bundle to receive this data in my MainActivityand I get an exception NullPointerException when I receive this data.

Intent code, from Fragment class

//Intent
Intent intent = new Intent(getContext(), MainActivity.class);
String [] names = new String [pets.size()];
int []likesNumber = new int[pets.size()];
int [] photo = new int [pets.size()];
for (int i = 0;i<pets.size();i++){
    names [i] = pets.get(i).getPetName();
    likesNumber [i]=pets.get(i).getNumberOfLikes();
    photo[i] = pets.get(i).getFoto();
}
intent.putExtra(getString(R.string.pet_name),names);
intent.putExtra(getString(R.string.numberOfLikes),likesNumber);
intent.putExtra(getString(R.string.photo),photo);
startActivity(intent);

Bundle code to receive the data in MainActivity class:

//Bundle para initialize pets
Bundle bundle = getIntent().getExtras();
String [] names = bundle.getStringArray(getString(R.string.pet_name));
int [] nLikes = bundle.getIntArray(getString(R.string.numberOfLikes));
int [] photo  = bundle.getIntArray(getString(R.string.photo));
for (int i = 0; i<names.length;i++){
    pets.add(new Pet(nLikes[i],names[i],photo[i]));
}

I get the exception in this line:

String [] names = bundle.getStringArray(getString(R.string.pet_name));

I don't know the reason why I get a NullPointerException, because all the references are ok. If it's a logic error I wish you'd tell me too.

I don't know if it it's important but I commented that my Fragment is composed of a RecyclerView

The error is as follows:

08-26 15:07:03.640 2551-2551/es.uclm.mylittlepets E/AndroidRuntime: FATAL EXCEPTION: main Process: es.uclm.mylittlepets, PID: 2551 java.lang.RuntimeException: Unable to start activity ComponentInfo{es.uclm.mylittlepets/es.uclm.mylittlepets.Layout.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String[] android.os.Bundle.getStringArray(java.lang.String)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String[] android.os.Bundle.getStringArray(java.lang.String)' on a null object reference at es.uclm.mylittlepets.Layout.MainActivity.onCreate(MainActivity.java:55) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

The way I solve this error:

IN MY Fragment CLASS:

1.- I've created an interface FragmentIterationListener that I'll use to communicate with the Activity

public interface FragmentIterationListener{
    public void onFragmentIteration(Bundle parameters);
}

We create a private FragmentIterationListener mcallback attribute which we are going to use to send data to Activity.

2.- In onAttach(Activity activity) method we'll do the following:

try {
        mcallback = (FragmentIterationListener) activity;
    }catch(ClassCastException ex){
        Log.e("PetsFragment","The activity must implement the FragmentIterationListener interface");
    }

Thus, we assign to our attribute the Activity that is going to communicate.

3.- In the onCreateView() method, besides inflating the Layout, we instantiate the RecyclerView.

recyclerView = (RecyclerView) view.findViewById(R.id.rvPets);

4.- In the onViewCreated() method, we establish the RecyclerView as a LinearLayout, then we initialize the ArrayList <Pet> pets and then we send it to MainActivity class:

Bundle extras = new Bundle();
extras.putParcelableArrayList("EXTRA_PETS", pets);
mcallback.onFragmentIteration(extras);

IN MY MainActivity.java CLASS:

1.- We implement the interface that we created earlier.

public class MainActivity extends AppCompatActivity implements PetsFragment.FragmentIterationListener{

2.- We implement the required method of this interface:

public void onFragmentIteration(Bundle parameters) {
    pets = parameters.getParcelableArrayList("EXTRA_PETS");
}

3.- We receive the data as follows: (in onCreate() method):

Bundle bundle = new Bundle();
onFragmentIteration(bundle);

It is not a duplicate, seems he has issue with accessing resources in Fragments. — sumandas, Aug 26 '16 at 15:23
I guess my question is not duplicated. At least I can't find another similar question that can help me — Iván García, Aug 26 '16 at 15:28
i think you have a problem of context , getting context of your activity from fragment . can you try this please : String [] names = bundle.getStringArray(getResources().getString(R.string.pet_name)); try to add some log.v to test if getString(R.string.pet_name) returning a string befor you start activity — MedAmine.Rihane, Aug 26 '16 at 15:34
could you post your code on github and send me the link . i want to help you . — MedAmine.Rihane, Aug 26 '16 at 15:43
In your fragment data is not passed using bundle .You have put data in bundle and pass that bundle to MainActivity — Mayurkumar Nevase, Aug 26 '16 at 16:53
And how can I do it? I think I don't understand what you want to tell me — Iván García, Aug 26 '16 at 22:15

Error when I try to send variables with Intent - NullPointerException

0 Answers0