Develop Reference

Hi! I am new to android app development. I tried to create a simple counter but after build getting error "Unable to instantiate activity"

public abstract class MainActivity extends AppCompatActivity {
Button decrement;
Button increment;
TextView counter_view;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Log.i("tag", "onCreate: Created Successfully");
increment=findViewById(R.id.inc_btn);
decrement=findViewById(R.id.dec_btn);
counter_view=findViewById(R.id.counter);
increment.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String cnt_text=counter_view.getText().toString();
int cnt_no= Integer.parseInt(cnt_text);
cnt_no=cnt_no+1;
counter_view.setText(cnt_no+"");
}
});
decrement.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String cnt_text=counter_view.getText().toString();
int cnt_no=Integer.parseInt(cnt_text);
cnt_no=cnt_no-1;
counter_view.setText(cnt_no+"");
}
});
}
Error:
2021-02-10 00:29:06.870 16714-16714/? E/Zygote: v2
2021-02-10 00:29:06.871 16714-16714/? E/Zygote: accessInfo : 0
2021-02-10 00:29:07.017 16714-16714/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.counter_app, PID: 16714
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.counter_app/com.example.counter_app.MainActivity}: java.lang.InstantiationException: java.lang.Class<com.example.counter_app.MainActivity> cannot be instantiated
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2849)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3045)
at android.app.ActivityThread.-wrap14(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1642)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6776)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1518)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)
Caused by: java.lang.InstantiationException: java.lang.Class<com.example.counter_app.MainActivity> cannot be instantiated
at java.lang.Class.newInstance(Native Method)
at android.app.Instrumentation.newActivity(Instrumentation.java:1086)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2839)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3045) 
at android.app.ActivityThread.-wrap14(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1642) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6776) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1518) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408) 

I suppose this is your first screen/activity/class that is displayed on launch i.e it is your launcher activity. If yes,
the launcher activity cannot be abstract. Because when an app is launched from the home screen on an Android device, the Android OS creates an instance of the activity in the application you have declared to be the launcher activity. And abstract classes can not be instantiated, they can only be sub-classed.
Please remove the word abstract before your class name.

add to your manifest file this line
<activity android:name="your.package.name.MainActivity"/>

Initialize an interface in an Activity

How can I initialize an interface in the MainActivity?
I have tried it like the following, but it keeps giving error.
MainActivity:
public class MainActivity extends AppCompatActivity {
private static final Logger LOG = LoggerFactory.getLogger("MainActivity");
private ExpandableListView mExpandableListView;
private ExpandableListViewAdapter mExpandableListViewAdapter;
private List<String> mListDataGroup;
private HashMap<String, List<String>> mListDataChild;
PreselectionAplicationUseCases preselectionAplicationUseCases;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initViews();
initListeners();
initObjects();
initListData();
preselectionAplicationUseCases=(PreselectionAplicationUseCases) this;
}
Interface:
public interface PreselectionAplicationUseCases {
void setOnMsgPreselectionChanged(MSG0100.OnMsg100PreselectionChanged listener);
void setMsg100PreselectionAplication(boolean msg100PreselectionAplication);
}
Errors:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: game, PID: 18315
java.lang.RuntimeException: Unable to start activity ComponentInfo{game/game.MainActivity}: java.lang.ClassCastException: game.MainActivity cannot be cast to game.usecases.PreselectionAplicationUseCases
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2327)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2389)
at android.app.ActivityThread.access$800(ActivityThread.java:153)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1305)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5271)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)
Caused by: java.lang.ClassCastException: game.MainActivity cannot be cast to game.usecases.PreselectionAplicationUseCases
at game.MainActivity.onCreate(MainActivity.java:96)
at android.app.Activity.performCreate(Activity.java:6033)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2280)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2389) 
at android.app.ActivityThread.access$800(ActivityThread.java:153) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1305) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5271) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)

The problem is this: preselectionAplicationUseCases=(PreselectionAplicationUseCases) this;
You cannot cast MainActivity to PreselectionAplicationUseCases since MainActivity or any of it's superclasses don't extend PreselectionAplicationUseCases.

MainActivity cannot be cast to android.app.Activity

I know this has been asked multiple times, and I been trying to fix it, but I really can't seem to understand what the problem is. I'm really new to Android Studio and Android Room, so if I'm honest, I barely have a clue what I'm doing. I assume the error occurs in my "MainActivity.java" class based off what the logcat tells me. This is my logcat
2020-06-15 01:33:41.885 21773-21773/com.example.hoply5 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.hoply5, PID: 21773
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.hoply5/com.example.hoply5.MainActivity}: java.lang.ClassCastException: com.example.hoply5.MainActivity cannot be cast to android.app.Activity
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3272)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3500)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2049)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7523)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:941)
Caused by: java.lang.ClassCastException: com.example.hoply5.MainActivity cannot be cast to android.app.Activity
at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:95)
at androidx.core.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:41)
at android.app.Instrumentation.newActivity(Instrumentation.java:1253)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3260)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3500) 
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2049) 
at android.os.Handler.dispatchMessage(Handler.java:106) 
at android.os.Looper.loop(Looper.java:223) 
at android.app.ActivityThread.main(ActivityThread.java:7523) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:941) 
Here is my MainActivity class
public class SecondFragment extends Fragment {
EditText editTxtName, editTxtEmail, editTxtPwd, editTextCnfPwd;
Button backBtn, registerBtn;
private UserDao userDao;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_second, container, false);
editTxtName = view.findViewById(R.id.editName);
editTxtEmail = view.findViewById(R.id.editEmail);
editTxtPwd = view.findViewById(R.id.editPwd);
registerBtn = view.findViewById(R.id.registerBtn2);
editTextCnfPwd = view.findViewById(R.id.editCnfPwd);
backBtn = view.findViewById(R.id.backBtn);
backBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), MainActivity.class);
startActivity(intent);
}
});
userDao = Room.databaseBuilder(getActivity(), UserDatabase.class, "User").build().getUserDao();
registerBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String userName = editTxtName.getText().toString().trim();
String email = editTxtEmail.getText().toString().trim();
String password = editTxtPwd.getText().toString().trim();
String passwordCnf = editTextCnfPwd.getText().toString().trim();
if(password.equals(passwordCnf)) {
User user = new User(userName,password,email);
userDao.insert(user);
Intent transitionLogin = new Intent(getActivity(), MainActivity.class);
startActivity(transitionLogin);
} else {
Toast.makeText(getActivity(), "Password is not matching", Toast.LENGTH_SHORT).show();
}
}
});
return view;
}
}

Your MainActivity is Fragment,so you have to replace it

Android java.lang.NullPointerException error with BroadcastReceiver

Everytime the application gets to my second activity it crashes, giving the error.
My activity:
public class SecondActivity extends AppCompatActivity {
EditText barcodeText = findViewById(R.id.barcodeText);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
IntentFilter filter = new IntentFilter();
filter.addCategory(Intent.CATEGORY_DEFAULT);
filter.addAction(getResources().getString(R.string.activity_intent_filter_action));
registerReceiver(myBroadcastReceiver, filter);
}
private BroadcastReceiver myBroadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Bundle b = intent.getExtras();
if (action.equals(getResources().getString(R.string.activity_intent_filter_action))) {
try {
displayScanResult(intent);
} catch (Exception e) {
}
}
}
};
private void displayScanResult(Intent initiatingIntent)
{
String decodedSource = initiatingIntent.getStringExtra(getResources().getString(R.string.datawedge_intent_key_source));
String decodedData = initiatingIntent.getStringExtra(getResources().getString(R.string.datawedge_intent_key_data));
String decodedLabelType = initiatingIntent.getStringExtra(getResources().getString(R.string.datawedge_intent_key_label_type));
barcodeText.setText(decodedData);
}
}
Logcat:
07-01 12:37:03.373 349-349/com.example.provatimer E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.provatimer, PID: 349
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.provatimer/com.example.provatimer.SecondActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2236)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5256)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
at android.content.ContextWrapper.getApplicationInfo(ContextWrapper.java:149)
at android.view.ContextThemeWrapper.getTheme(ContextThemeWrapper.java:99)
at android.content.Context.obtainStyledAttributes(Context.java:438)
at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:692)
at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:659)
at androidx.appcompat.app.AppCompatDelegateImpl.findViewById(AppCompatDelegateImpl.java:479)
at androidx.appcompat.app.AppCompatActivity.findViewById(AppCompatActivity.java:214)
at com.example.provatimer.SecondActivity.<init>(SecondActivity.java:14)
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1606)
at android.app.Instrumentation.newActivity(Instrumentation.java:1066)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2226)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5256) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699) 
I think it may have something to do with the context in the BroadcastReceiver, but I tried to declare it in the onCreate method but nothing changed.
Maybe I don't initialize correctly the intent in which the data should be stored, if so, how can I do it correctly?
All the Strings should be correct int the string.xml file, if the error may come from that I'll write them.

I think the error is happening here:
EditText barcodeText = findViewById(R.id.barcodeText);
You are invoking findViewById() directly in the class member declaration.
You have invoke findViewById() after setContentView()
EditText barcodeText;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
barcodeText = findViewById(R.id.barcodeText);
}

Retrofit2 java null pointer object reference

Hi I am trying to parse JSON using Retrofit, save it on Sqlite and display on RecyclerView. However my app crashes when I try to open the activity.
Below is my full codes of related activity. Could you please help me with resolving the issue?
Thank you
public class InventoryProductActivity extends AppCompatActivity implements InventoryProductListAdapter.CustomClickListener {
private static final String TAG = InventoryProductActivity.class.getSimpleName();
private InventoryProductListAdapter mInventoryProductListAdapter;
private RecyclerView mRecyclerView;
private RetrofitClient mRetrofitClient;
LinearLayoutManager mLinearLayoutManager;
private WarehouseDatabase mDatabase;
private ProgressDialog mProgressDialog;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_inventory_product);
configViews();
mRetrofitClient = new RetrofitClient();
mDatabase = new WarehouseDatabase(this);
loadInventoryProductFeed();
}
private void configViews() {
mRecyclerView = findViewById(R.id.recycler_view_inventory_product);
mRecyclerView.setHasFixedSize(true);
mLinearLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLinearLayoutManager);
mInventoryProductListAdapter = new InventoryProductListAdapter(this);
mRecyclerView.setAdapter(mInventoryProductListAdapter);
}
private void loadInventoryProductFeed() {
mProgressDialog = new ProgressDialog(InventoryProductActivity.this);
mProgressDialog.setMessage("Loading Inventory Data...");
mProgressDialog.setCancelable(true);
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
mProgressDialog.setIndeterminate(true);
mProgressDialog.show();
mInventoryProductListAdapter.reset();
if (getNetworkAvailability()) {
getFeed();
} else {
getFeedFromDatabase();
}
}
private void getFeed() {
Call<List<InventoryProductModel>> listCall = mRetrofitClient.getWarehouseServiceInventoryProduct().getAllInventoryProducts();
listCall.enqueue(new Callback<List<InventoryProductModel>>() {
#Override
public void onResponse(Call<List<InventoryProductModel>> call, Response<List<InventoryProductModel>> response) {
if (response.isSuccessful()) {
List<InventoryProductModel> inventoryProductModelList = response.body();
for (int i = 0; i < inventoryProductModelList.size(); i++) {
InventoryProductModel inventoryProductModel = inventoryProductModelList.get(i);
mInventoryProductListAdapter.notifyDataSetChanged();
}
} else {
int sc = response.code();
switch (sc) {
}
}
mProgressDialog.dismiss();
}
#Override
public void onFailure(Call<List<InventoryProductModel>> call, Throwable t) {
mProgressDialog.dismiss();
Toast.makeText(getApplicationContext(), t.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
private void getFeedFromDatabase() {
List<InventoryProductModel> inventoryProductModelList = mDatabase.getInventoryProducts();
for (int i = 0; i < inventoryProductModelList.size(); i++) {
InventoryProductModel inventoryProductModel = inventoryProductModelList.get(i);
Log.d(TAG, inventoryProductModel.getName() + "||" + inventoryProductModel.getCountryId());
}
mProgressDialog.dismiss();
}
private boolean getNetworkAvailability() {
return Utils.isNetworkAvailable(getApplicationContext());
}
#Override
public void onClick(int position) {
}
}
E/WindowManager: android.view.WindowLeaked: Activity
codes.bala.bmsfinal1.activity.MainActivity has leaked window
DecorView#52c3fcd[] that was originally added here
at android.view.ViewRootImpl.(ViewRootImpl.java:418)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:331)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:93)
at android.app.Dialog.show(Dialog.java:322)
at android.app.ProgressDialog.show(ProgressDialog.java:116)
at android.app.ProgressDialog.show(ProgressDialog.java:104)
at codes.bala.bmsfinal1.activity.MainActivity.login(MainActivity.java:61)
at codes.bala.bmsfinal1.activity.MainActivity$1.onClick(MainActivity.java:41)
at android.view.View.performClick(View.java:5637)
at android.view.View$PerformClick.run(View.java:22429)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
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$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
I/ViewConfigCompat: Could not find method getScaledScrollFactor() on
ViewConfiguration D/AndroidRuntime: Shutting down VM
--------- beginning of crash E/AndroidRuntime: FATAL EXCEPTION: main
Process: codes.bala.bmsfinal1, PID: 12077
java.lang.RuntimeException: Unable to start activity ComponentInfo{codes.bala.bmsfinal1/codes.bala.bmsfinal1.activity.InventoryProductActivity}:
java.lang.NullPointerException: Attempt to invoke interface method
'retrofit2.Call
codes.bala.bmsfinal1.iinterface.WarehouseService.getAllInventoryProducts()'
on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$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$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.NullPointerException: Attempt to invoke interface
method 'retrofit2.Call
codes.bala.bmsfinal1.iinterface.WarehouseService.getAllInventoryProducts()'
on a null object reference
at codes.bala.bmsfinal1.activity.InventoryProductActivity.getFeed(InventoryProductActivity.java:88)
at codes.bala.bmsfinal1.activity.InventoryProductActivity.loadInventoryProductFeed(InventoryProductActivity.java:70)
at codes.bala.bmsfinal1.activity.InventoryProductActivity.onCreate(InventoryProductActivity.java:46)
at android.app.Activity.performCreate(Activity.java:6679)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726) 
at android.app.ActivityThread.-wrap12(ActivityThread.java) 
at android.app.ActivityThread$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) 
Application terminated.

getWarehouseServiceInventoryProduct()
method return null.
You should set breakpoint inside this method and check what happening (or add some logs to this method).