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How can I get an order id from Firestore and pass it to my adaptor class?

I need to get an order id from Firestore and pass that id to my Query but I'm getting the order id happens asynchronously. So I am forced to initialize my adaptor inside the Firebase callback method. The issue is that my onStart and onStop methods are listening on the adaptor and then throws a NullPointException.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_to_cart);
// Navigate to men section
fromAddToCartToForHim = findViewById(R.id.fromAddToCartToForHim);
fromAddToCartToForHim.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(AddToCart.this, HimActivity.class);
startActivity(intent);
finish();
}
});
//Navigate to Women section
fromAddToCartToForHer = findViewById(R.id.fromAddToCartToForHer);
fromAddToCartToForHer.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(AddToCart.this, WomenActivity.class);
startActivity(intent);
finish();
}
});
// Navigate to Household section
fromAddToCartToForHouseHold = findViewById(R.id.fromAddToCartToForHouseHold);
fromAddToCartToForHouseHold.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(AddToCart.this, HouseHoldActivity.class);
startActivity(intent);
finish();
}
});
// SetUpRecyclerView func
setUpRecycleView();
}
private void setUpRecycleView() {
// GET CURRENT ORDER ID
orderRef.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
#Override
public void onComplete(#NonNull #NotNull Task<QuerySnapshot> task) {
if (task.isComplete()) {
QuerySnapshot snapshot = task.getResult();
assert snapshot != null;
for (DocumentSnapshot snapshots : snapshot.getDocuments()) {
String user_id = snapshots.getString("user_id");
Boolean status = snapshots.getBoolean("status");
if (user_id.equals(getUserId()) && !status) {
// User has existing Order
// Check if order is pending or completed
String orderId = snapshots.getId();
Query query = orderRef
.document(orderId)
.collection("orderlist")
.orderBy("category").orderBy("priority", Query.Direction.ASCENDING);
FirestoreRecyclerOptions<OrderList> options = new FirestoreRecyclerOptions.Builder<OrderList>()
.setQuery(query, OrderList.class)
.build();
addToCartAdaptor = new AddToCartAdaptor(options);
recyclerView = findViewById(R.id.recyclerviewAddToCart);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(AddToCart.this));
recyclerView.setAdapter(addToCartAdaptor);
}
}
}
}
});
}
enter code here
#Override
protected void onStart() {
super.onStart();
addToCartAdaptor.startListening(); Error happens here
}
#Override
protected void onStop() { `enter code here`
super.onStop();
addToCartAdaptor.stopListening();
}
HERE IS THE ERROR I GET
W/example.neptun: Accessing hidden method Lcom/msic/qarth/PatchStore;->createDisableExceptionQarthFile(Ljava/lang/Throwable;)Z (blacklist, JNI)
E/example.neptun: [qarth_debug:] get PatchStore::createDisableExceptionQarthFile method fail.
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.neptune, PID: 2884
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.example.neptune.Adapters.AddToCartAdaptor.startListening()' on a null object reference
at com.example.neptune.AddToCart.onStart(AddToCart.java:150)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1419)
at android.app.Activity.performStart(Activity.java:7479)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3454)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:180)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:165)
at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:142)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:70)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2199)
at android.os.Handler.dispatchMessage(Handler.java:112)
at android.os.Looper.loop(Looper.java:216)
at android.app.ActivityThread.main(ActivityThread.java:7625)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:987)
I/Process: Sending signal. PID: 2884 SIG: 9

When you are using the following line of code:
addToCartAdaptor = new AddToCartAdaptor(options);
Inside the "onComplete()" method, it means it will always run right after the onStart, as it takes some time to get the data from the orderRef reference. What you can do, is to create the (default) Query, FirestoreRecyclerOptions, and AddToCartAdaptor objects outside the onComplete() method, and once you get the data inside the callback, simply update the "options" object, with the data that you get from the database. In this way, you provide the data to the "options" object, only when it is available.
This also means that you'll never get a NullPointerException anymore because the addToCartAdaptor is already initialized.

How to move reusable functionalities to a generic class and invoke another activity from there?

I am new to Android development and I am facing an issue in invoking an activity from a generic class where I have a reusable function.
I have MainActivity where I need to check if the application has Network connectivity and then check if the user is already signed in.
If the user is signed in I need to open the Rate activity otherwise I will open the Login activity.
I thought I can keep the logic that checks the Network connectivity and shows the popup reusable and move it to a Global class as below
public class Global extends AppCompatActivity {
public static boolean hasConnectivity = false;
public static boolean userSignedIn = false;
String TAG = "Debug Log - Helper";
Context context;
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
context = this;
}
private void networkConnectionErrorDialog(final Context context, final Class targetClass){
Log.d(TAG, "Show Alert Dialog");
new AlertDialog.Builder(context)
.setTitle(R.string.connection_error_title)
.setMessage(R.string.connection_error_message)
.setIcon(R.drawable.warning)
.setPositiveButton(
R.string.try_again,
new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
Log.d(TAG, "Trying Again");
isNetworkAvailable(context, targetClass);
}
}).show();
}
protected void isNetworkAvailable(Context context, Class targetClass) {
if(NetworkUtil.isConnected(context)){
Log.d(TAG, "Has connectivity");
if(targetClass != null){
Log.d(TAG, targetClass.toString());
Intent targetIntent = new Intent(context, targetClass);
startActivity(targetIntent);
}
hasConnectivity = true;
return;
}else{
Log.d(TAG, "Has no connectivity");
hasConnectivity = false;
networkConnectionErrorDialog(context, targetClass);
}
}
}
I pass in the targetClass as Login.class or Rate.class (based on user signed in state) from the MainActivity where isNetworkAvailable() is invoked.
I am getting the following error. Could someone help me fix the issue and help me understand if my approach needs improvement?
java.lang.RuntimeException: Unable to resume activity {com.solitontech.dayatsoliton/com.solitontech.dayatsoliton.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.app.ActivityThread$ApplicationThread android.app.ActivityThread.getApplicationThread()' on a null object reference
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3581)
at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3621)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2862)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.app.ActivityThread$ApplicationThread android.app.ActivityThread.getApplicationThread()' on a null object reference
at android.app.Activity.startActivityForResult(Activity.java:4488)
at android.support.v4.app.BaseFragmentActivityJB.startActivityForResult(BaseFragmentActivityJB.java:50)
at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:79)
at android.app.Activity.startActivityForResult(Activity.java:4445)
at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:859)
at android.app.Activity.startActivity(Activity.java:4806)
at android.app.Activity.startActivity(Activity.java:4774)
at com.solitontech.dayatsoliton.Global.isNetworkAvailable(Global.java:50)
at com.solitontech.dayatsoliton.MainActivity.onResume(MainActivity.java:68)
at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1355)
at android.app.Activity.performResume(Activity.java:7117)
at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3556)

It looks like your application is experiencing a null pointer exception in your activity's onResume method. If you had called startActivityForResult, make sure that the data in
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{..}
is non null before processing it.
As for your question about starting an activity from your helper class Global, you can define a function like this.
private static void goToActivity(Context context, Class<?> activityClass){
Intent intent = new Intent(context, activityClass);
context.startActivity(intent);
}
You can call this method as below.
goToActivity(context,TargetActivity.class);
Good luck.

Intent targetIntent = new Intent(context, targetClass);
startActivity(targetIntent);
above code is wrong. You should pass your current activity and target activity here.
Intent intent = new Intent(CurrentActivity.this, TargetingActivity.class);
startActivity(intent);
As a example :
If you want to start ActivtyB form ActivtyA
Intent intent = new Intent(ActivityA.this, ActivityD.class);
startActivity(intent);
1st try to correct this error. then you can find some others.

Null Error attempting to create an intent in AsyncTask

Apologizes if this is a stupid question but I'm attempting to create a Intent to the next activity in AsynTask after it has pulled a user from my AWS Database. Note that this class is HomeActivity and the next one is GroupActivity. Below I have the button that will run the AsynTask:
Button groupPageBtm = findViewById(R.id.groupPage);
groupPageBtm.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
LoadGroupUser loadGroupUser = new LoadGroupUser(HomeActivity.this);
loadGroupUser.execute(makeUserIDString.uniqueIDCreater(userProfile));
}
});
Here is my AsynTask subclass:
class LoadGroupUser extends AsyncTask<String, Void, GroupDO>{
private DynamoDBMapper dynamoDBMapper;
Activity activity;
public LoadGroupUser(Activity mActivity){
this.activity = mActivity;
}
Intent groupLoadIntent = new Intent(activity, GroupActivity.class);
#Override
protected GroupDO doInBackground(String... groupPresidentGroups) {
AmazonDynamoDBClient dynamoDBClient = new AmazonDynamoDBClient(AWSMobileClient.getInstance().getCredentialsProvider());
this.dynamoDBMapper = DynamoDBMapper.builder()
.dynamoDBClient(dynamoDBClient)
.awsConfiguration(AWSMobileClient.getInstance().getConfiguration())
.build();
GroupDO groupPresDO = dynamoDBMapper.load(GroupDO.class, groupPresidentGroups[0]);
Log.i("loadedPresident: ", groupPresDO.getGroupId().toString());
return null;
}
#Override
protected void onPostExecute(GroupDO groupDO) {
super.onPostExecute(groupDO);
groupLoadIntent.putExtra("groupPresident", groupDO.getGroupPresident().toString());
activity.startActivity(groupLoadIntent);
Log.i("groupPresident", groupDO.getGroupPresident().toString());
}
}
Error Message:
-12 17:02:59.424 10503-10503/com.ronone.securesender E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.ronone.securesender, PID: 10503
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
at android.content.ComponentName.<init>(ComponentName.java:130)
at android.content.Intent.<init>(Intent.java:5780)
at com.ronone.securesender.LoadGroupUser.<init>(HomeActivity.java:188)
at com.ronone.securesender.HomeActivity$1.onClick(HomeActivity.java:77)
at android.view.View.performClick(View.java:6294)
at android.view.View$PerformClick.run(View.java:24770)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

The problem is here:
public LoadGroupUser(Activity mActivity){
this.activity = mActivity;
}
Intent groupLoadIntent = new Intent(activity, GroupActivity.class);
The field initializer runs before the constructor, so activity is still null. Do this instead:
Intent groupLoadIntent;
public LoadGroupUser(Activity mActivity){
this.activity = mActivity;
groupLoadIntent = new Intent(activity, GroupActivity.class);
}
But note that you're potentially leaking your activity by having a strong reference to it in an AsyncTask. That's a whole other topic. Search this site for "AsyncTask activity leak."

Android Retrofit "Attempt to invoke virtual method on a null object reference"

Hi first of all i searched some similar questions like mine but unfortunately i couldn't find the similarity of my code to them so please here me out
I have a Main Activity Class
public class MainActivity extends AppCompatActivity {
public ProgressDialog loading;
public String[] itemer;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RetrofitHandler handler = new RetrofitHandler();
handler.getContacts(MainActivity.this);
}
public void getter(String[] response, int size) {
String[] itemer;
itemer = new String[size];
if (response != null) {
itemer = response;
Toast.makeText(MainActivity.this, itemer[0], Toast.LENGTH_SHORT).show();
}
}
And a Handler for my result
public class RetrofitHandler {
public String[] item;
public static final String ROOT_URL = "http://api.androidhive.info";
public List<Contacts> contacts;
// final MainActivity main = new MainActivity();
public void getContacts(final Context context) {
final ProgressDialog loading = ProgressDialog.show(context, "Fetching Data", "Please wait...", false, false);
RestAdapter adapter = new RestAdapter.Builder().setEndpoint(ROOT_URL).build();
ContactsAPI api = adapter.create(ContactsAPI.class);
api.getContacts(new Callback<Contacts>() {
#Override
public void success(Contacts contacts, Response response) {
loading.dismiss();
MainActivity update = new MainActivity();
List<Contact> contactList = contacts.getContacts();
item = new String[contactList.size()];
int size = contactList.size();
for (int i = 0; i < contactList.size(); i++) {
item[i] = contactList.get(i).getName();
}
update.getter(item, size);
}
#Override
public void failure(RetrofitError error) {
Toast.makeText(context, "Error Occured", Toast.LENGTH_LONG).show();
}
});
}
But I get an error on my response in the main activity here is my log
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
at android.content.ContextWrapper.getResources(ContextWrapper.java:87)
at android.view.ContextThemeWrapper.getResources(ContextThemeWrapper.java:81)
at android.support.v7.app.AppCompatActivity.getResources(AppCompatActivity.java:542)
at android.widget.Toast.<init>(Toast.java:102)
at android.widget.Toast.makeText(Toast.java:259)
at com.exist.kelvs.retrofit2.MainActivity.getter(MainActivity.java:55)
at com.exist.kelvs.retrofit2.RetrofitHandler$1.success(RetrofitHandler.java:41)
at com.exist.kelvs.retrofit2.RetrofitHandler$1.success(RetrofitHandler.java:28)
at retrofit.CallbackRunnable$1.run(CallbackRunnable.java:45)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
I maked sure that the handler item where not null tested it with toast but when i pass it to getter it gives me the error where did i do wrong? :(

MainActivity update = new MainActivity();
Never instantiate activities with new. They are not initialized to be useful.
Instead, you can pass your activity as a reference where needed. Change
public void getContacts(final Context context)
to e.g.
public void getContacts(final MainActivity mainActivity)
and use mainActivity where you need an activity Context (such as with Dialogs) and when you need to invoke a method on MainActivity.
Note that generally passing activity references to async operations can be prone to significant memory leaks, and you need to take activity lifecycle into account - the activity might not be active when the async operation finishes.

try to delete the toast in your main activity or replace Mainactivity.this to getApplicationContext() .
from :
Toast.makeText(MainActivity.this, itemer[0], Toast.LENGTH_SHORT).show();
to :
Toast.makeText(getApplicationContext(), itemer[0], Toast.LENGTH_SHORT).show();

Could not find method in a parent or ancestor Context for android:onClick attribute defined on view class android.widget.ImageView

I basically just call this in the android:onClick function in my XML for this particular ImageView: android:onClick="SendGetStartedNotification". But because my function has two parameters, I get this error Method has incorrect signature. It wants me to removed the ParseUser class.
public void SendGetStartedNotification(View view, ParseUser user) {
// initiate installation query
ParseQuery<ParseInstallation> query = ParseInstallation.getQuery();
query.whereEqualTo("userId", user.getUserObject());
// send push notification
ParsePush push = new ParsePush();
push.setQuery(query);
push.setMessage(ParseUser.getCurrentUser().getUsername() + " " + "thinks you should create something!");
push.sendInBackground();
// send notification to NotificationsActivity
ParseObject notification = createGetStartedMessage(view, user);
send(notification);
}
The problem is my error message:
12-20 22:22:37.349 29251-29251/com.app.testE/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.app.test, PID: 29251
java.lang.IllegalStateException: Could not find method SendGetStartedNotification(View) in a parent or ancestor Context for android:onClick attribute defined on view class android.widget.ImageView with id 'messageGallerySave2'
at android.view.View$DeclaredOnClickListener.resolveMethod(View.java:4485)
at android.view.View$DeclaredOnClickListener.onClick(View.java:4449)
at android.view.View.performClick(View.java:5204)
at android.view.View$PerformClick.run(View.java:21153)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
What are my alternatives? Setting an onClick listener programatically doesn't seem to be working either. What should I do?
Update: I'm using an AsyncTask to bring user information in my class.
private class GetParseUserInformationTask extends AsyncTask<Void, Design, ParseUser> {
#Override
protected void onPreExecute() {
super.onPreExecute();
mProgressDialog = new ProgressDialog(GalleryActivity.this);
// Set progressdialog message
mProgressDialog.setMessage("Loading Designs...");
mProgressDialog.setIndeterminate(false);
// Show progressdialog
mProgressDialog.show();
}
#Override
protected ParseUser doInBackground(Void... params) {
ParseUser parseUser = null;
// gather User information and then fetch the designs for them
try {
parseUser = ParseHelper.GetUserInformation(userObjectId);
} catch (ParseException e) {
e.printStackTrace();
}
return parseUser;
}
#Override
protected void onPostExecute(ParseUser user) {
if(user == null) {
//todo: some error message
return;
}
((TextView)findViewById(R.id.fullName)).setText(user.getName());
((TextView)findViewById(R.id.bio)).setText(user.getBio());
((TextView)findViewById(R.id.websiteLink)).setText(user.getWebsiteLink());
((TextView)findViewById(R.id.username)).setText(user.getUsername());
((TextView)findViewById(R.id.saves_number)).setText(user.getFeedDesignSaves().toString());
((TextView)findViewById(R.id.designs_number)).setText(String.valueOf(ParseHelper.GetUserDesignsCount(user.getUserObject())));
((ImageView)findViewById(R.id.profile_picture)).setImageDrawable(Drawable.createFromPath(user.getProfilePictureURL()));
// asynchronously display the profile picture downloaded from parse
if(user.getProfilePictureURL() != null) {
profilePictureImageLoader.DisplayImage(user.getProfilePictureURL(), ((ImageView) findViewById(R.id.profile_picture)), null);
}
new GetParseUserDesignsTask().execute(user);
mProgressDialog.dismiss();
}
}

On Click listener on button.
imageView.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
// TODO Auto-generated method stub
SendGetStartedNotification(ParseUser user);
}
} );
Make your method like this:
public void SendGetStartedNotification(ParseUser user) {
// initiate installation query
ParseQuery<ParseInstallation> query = ParseInstallation.getQuery();
query.whereEqualTo("userId", user.getUserObject());
// send push notification
ParsePush push = new ParsePush();
push.setQuery(query);
push.setMessage(ParseUser.getCurrentUser().getUsername() + " " + "thinks you should create something!");
push.sendInBackground();
// send notification to NotificationsActivity
ParseObject notification = createGetStartedMessage(view, user);
send(notification);
}