Failed to retrieve ArrayList from a separate class

Question

I have a DataHandaling class that is used to do the logic, it is also suppose to be an easier way to retrieve an ArrayList from multiple activities, But when I start a new activity the ArrayList is null

(NOTE: The array is not empty because I have used the same array multiple times in the main activity, this problem is only a case when I start a new activity)

The code from DataHandaling

public class DataHandaling {
    EnviroClass enviroClass = new EnviroClass();
    private ArrayList<Event> eventArray = new ArrayList<Event>();

    public ArrayList<Event> getEventArray() {
        return eventArray;
    }

    public void getEvents() {
        OkHttpClient client = new OkHttpClient();

        Request request = new Request.Builder()
                .url(enviroClass.url() + "/api/events/" + 7)
                .build();

        client.newCall(request)
                .enqueue(new Callback() {
                    @Override
                    public void onFailure(Call call, IOException e) {

                    }

                    @Override
                    public void onResponse(Call call, Response response) throws IOException {
                        try {
                            JSONObject eventObject = new JSONObject(response.body().string());
                            JSONArray eventJsonArray = eventObject.getJSONArray("events");
                            for (int i = 0; i<eventJsonArray.length(); i++) {
                                eventObject = eventJsonArray.getJSONObject(i);
                                eventObject = eventObject.getJSONObject("event");
                                eventArray.add(new Event(eventObject.getString("name"), eventObject.getString("address"), eventObject.getString("image"), "100" ,eventObject.getString("start_date"), eventObject.getString("end_date"), eventObject.getInt("id")));
                            }
                            EventListAdapter adapter = new EventListAdapter(null, null);
                            adapter.swap(eventArray);
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                });
    }

}

This is where it is breaking in the new activity

textView.setText(dh.getEventArray().get(0).getName());

The interaction listener to open the new activity

@Override
public void onListFragmentInteraction(int id) {
    Intent intent = new Intent(MainActivity.this, ProfileActivity.class);
    intent.putExtra("id", id);
    MainActivity.this.startActivity(intent);
}

The activity where it is breaking

public class ProfileActivity extends AppCompatActivity {

    DataHandaling dh = new DataHandaling();

    int eventArrayId;

    TextView eventDescription;
    TextView eventName;
    ImageView eventImage;

    ArrayList<Event> eventArray = new ArrayList<Event>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_profile);
        getSupportActionBar().setHomeButtonEnabled(true);

        Intent intent = getIntent();
        eventArrayId = intent.getIntExtra("id", 0);

        eventName = (TextView) findViewById(R.id.eventNameTextView);

        eventName.setText(dh.getEventArray().get(0).getName());

    }



}

Stack Trace:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.app.gb.socilizer_app/com.app.gb.socilizer.Activities.ProfileActivity}: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
                                                                                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
                                                                                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
                                                                                      at android.app.ActivityThread.-wrap12(ActivityThread.java)
                                                                                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
                                                                                      at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                      at android.os.Looper.loop(Looper.java:154)
                                                                                      at android.app.ActivityThread.main(ActivityThread.java:6119)
                                                                                      at java.lang.reflect.Method.invoke(Native Method)
                                                                                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
                                                                                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
                                                                                   Caused by: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
                                                                                      at java.util.ArrayList.get(ArrayList.java:411)
                                                                                      at com.app.garethbecker.socializer.Activities.ProfileActivity.onCreate(ProfileActivity.java:39)
                                                                                      at android.app.Activity.performCreate(Activity.java:6679)
                                                                                      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
                                                                                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
                                                                                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726) 
                                                                                      at android.app.ActivityThread.-wrap12(ActivityThread.java) 
                                                                                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477) 
                                                                                      at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                                      at android.os.Looper.loop(Looper.java:154) 
                                                                                      at android.app.ActivityThread.main(ActivityThread.java:6119) 
                                                                                      at java.lang.reflect.Method.invoke(Native Method) 
                                                                                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
                                                                                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

Do you want to pass this list between different Activities?? or just want to use it inside a single activity?? — sumit, Jun 09 '17 at 11:12
I'm trying to use it between 2 activities, The information in it is gotten from the server, So I didn't want to call 10 times for information coming from the same table in the database. — TheFairywarrior, Jun 09 '17 at 11:28
There we go, Though there are just the 2 methods, I know that the array isn't empty because I used that array in a `ListView` — TheFairywarrior, Jun 09 '17 at 11:35
You cannot simply get reference of the object creating new object. You need to write a code to use same instance everywhere. Learn the basics of objects and classes first. You are wrong at ProfileActivity first line: DataHandaling dh = new DataHandaling(); — Nabin Bhandari, Jun 09 '17 at 11:38

score 1 · Accepted Answer · answered Jun 09 '17 at 11:29

1

You are creating new object of DataHandling in the activity. So it will not be the same object that you had previously used and which has data in it.

answered Jun 09 '17 at 11:29

gprathour

14,813
5
66
90

Ahhhh so would it be a good idea to send it through as a ParcelableArrayListExtra??? – TheFairywarrior Jun 09 '17 at 11:38

Asew · Answer 2 · 2017-06-09T11:33:51.883

0

Your method is called getArray(), yet you're invoking getEventArray(). Maybe it is the reason.

EDIT: Now that your message is edit we have something to work on.

DataHandaling dh = new DataHandaling();

This is a new DataHandaling object, and never in your code you're updating him. So I guess that its ArrayList is empty by default.

edited Jun 09 '17 at 11:33

answered Jun 09 '17 at 11:05

Asew

374
2
13

No I was just typing out the code here instead of copying and pasting it xD, That would of helped me a lot if it was just that xD – TheFairywarrior Jun 09 '17 at 11:07
Ahah okay. So what error message are you getting ? – Asew Jun 09 '17 at 11:08
`java.lang.IndexOutOfBoundsException` which is weird because I used the same array a couple other times without a problem – TheFairywarrior Jun 09 '17 at 11:10
1

Can you edit your post and add the full stack trace ? Also can you provide the code section, and not just one line. The only thing I can tell you right now with the current information, is that your array is empty. – Asew Jun 09 '17 at 11:11
@TheMysticalWarrior Updated my answer. – Asew Jun 09 '17 at 11:34

score 0 · Answer 3 · answered Jun 09 '17 at 11:16

First :- If your ArrayList<Event> is empty and if you get 0th index element then you'll get NullPointerException while Executing this line :- dh.getEventArray().get(0).getName() so it is replaced by null.getName() which will break.

So if you want to get index basis Element form collection firsat checkl whether the Collection is empty or not. Like this:-

    //if the ArrayList is not Empty then only iterate over it.
    if(!dh.getEventArray().isEmpty())
    {
        textView.setText(dh.getEventArray().get(0).getName());
    }

Second:- Check the logic for adding the Event In ArrayList<Event>.

I know that the array isn't empty because I have used it before, It is only null when I open the new activity — TheFairywarrior, Jun 09 '17 at 11:25

Failed to retrieve ArrayList from a separate class

3 Answers3