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();
Related
Context is not a strong point of mine, I keep getting this error this is part of code i have moved over from another application and works in there just fine, however i am trying to transplant the code from the smaller app to this main app, as adding it as a library was causing headaches which are best sorted out another day.
So the error i receive is:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.app, PID: 12564
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
at androidx.localbroadcastmanager.content.LocalBroadcastManager.getInstance(LocalBroadcastManager.java:107)
at com.app.TManager.startUpdatingTrace(TManager.java:229)
at com.app.activities.ui.routeaction.RouteActionFragment$2.onFinish(RouteActionFragment.java:128)
at android.os.CountDownTimer$1.handleMessage(CountDownTimer.java:127)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
So this is the relevant code in TManager:
public class TManager extends AppCompatActivity implements Serializable {
BroadcastReceiver sensorReceiver;
BroadcastReceiver locationReceiver;
ExecutorService executorService = Executors.newFixedThreadPool(20);
public static Intent locationIntent;
public static Intent sensorService;
public LocalBroadcastManager localBroadcastManager;
public static MutableLiveData<Integer> status = new MutableLiveData<Integer>();
//Empty constructor
public TManager(){}
#RequiresApi(api = Build.VERSION_CODES.O)
public void startUpdating() {
status.setValue(0);
//register for sensorBroadcast
sensorReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
TCIMUEvent tcimuEvent = (TCIMUEvent) intent.getSerializableExtra("imuevent");
// Log.d(TAG, "In Motion Received "+ tcimuEvent.getTime());
Runnable provideDM = new Runnable() {
#Override
public void run() {
//traceCWrapper.provideDeviceMotion(tcimuEvent, Status, 0, RotationMode.Undetermined);
}
};
executorService.execute(provideDM);
}
};
localBroadcastManager.getInstance(MyApplication.getAppContext()).registerReceiver(
sensorReceiver, new IntentFilter("imuCreated")
);
//register for locationBroadcast
locationReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
TCLocationEvent tcLocationEvent = (TCLocationEvent) intent.getSerializableExtra("locationevent");
Runnable provideLoc = new Runnable() {
#Override
public void run() {
traceCWrapper.provideLocation(tcLocationEvent);
}
};
executorService.execute(provideLoc);
}
};
LocalBroadcastManager.getInstance(context).registerReceiver( //Error Here <-----
locationReceiver, new IntentFilter("locationCreated")
);
isRunning = true;
//Start the Services
AsyncTask as1 = new AsyncTask() {
#Override
protected Object doInBackground(Object[] objects) {
startUpdatingLocation();
return null;
}
}.execute();
AsyncTask as2 = new AsyncTask() {
#Override
protected Object doInBackground(Object[] objects) {
startUpdatingSensors();
return null;
}
}.execute();
}
}
This is just one example i keep getting these errors all through the code which was copied in another example error:
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.AssetManager android.content.Context.getAssets()' on a null object reference
It seeems to especially be where is use
MyApplication.getAppContext......
MyApplication just returns as below:
public class MyApplication extends Application {
private static Context context;
public void onCreate() {
super.onCreate();
MyApplication.context = getApplicationContext();
}
public static Context getAppContext() {
return MyApplication.context;
}
}
How do i resolve these issues? The whole classes have been moved over it is not code taken from one class dumped into another. So not sure why context should have changed.
As i was using the MyApplication static context class in some places i needed to add this line to my Manifest file within the tag
android:name="com.yourapp.app.yourapp.MyApplication"
and make sure the application class is placed in the top level main/java/com.yourapp.app.yourapp/
This worked for me and solved the issue throughout the App. I would pay attention to the comments made as this may well not be the best way to be using Context, however this solved my issue at the moment.
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.
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."
I have a second class from which I call some methods to handle app updating. There is a progress dialog in them so I have to pass the current application context to its constructor. The code works fine when called directly in my MainActivity onCreate(), but it breaks down when I delegate the code to an external class. What's going wrong?
Method Call in OnCreate():
private AppUpdateHelper appUpdateHelper = new AppUpdateHelper(getApplicationContext());
#Override
protected void onCreate(Bundle savedInstanceState) {
appUpdateHelper.handleAppUpdate();
}
Delegate Class:
public class AppUpdateHelper {
private Context mContext;
public AppUpdateHelper(Context mContext) {
this.mContext = mContext;
}
public void handleAppUpdate() {
String versionCode = getVersionCode(); // Get app's current version code
// Is app update to date?
if (isAppCurrent(versionCode)) {
promptAppUpdate();
}
}
private String getVersionCode() {
String versionCode = null;
try {
PackageInfo pInfo = mContext.getPackageManager().getPackageInfo(mContext.getPackageName(), 0);
versionCode = pInfo.versionName;
// Log.w(mContext.getClass().getSimpleName(), "Current Version: " + versionCode);
} catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
}
return versionCode;
}
private boolean isAppCurrent(String versionCode) {
ParseInstallation installation = ParseInstallation.getCurrentInstallation();
String userAppVersion = installation.getString("appVersion");
return !userAppVersion.equals(versionCode);
}
private void promptAppUpdate() {
SweetAlertDialog pDialog = new SweetAlertDialog(mContext, SweetAlertDialog.WARNING_TYPE);
pDialog.setTitleText("Update Available!");
pDialog.setContentText("You must update to continue using Yeet Club!");
pDialog.setConfirmClickListener(sDialog -> {
final String appPackageName = mContext.getPackageName(); // getPackageName() from Context or Activity object
try {
mContext.startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=" + appPackageName)));
} catch (ActivityNotFoundException anfe) {
mContext.startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("https://play.google.com/store/apps/details?id=" + appPackageName)));
}
sDialog.dismissWithAnimation();
});
pDialog.setCancelable(false);
pDialog.showCancelButton(false);
pDialog.show();
}
}
Exception:
08 - 20 15: 43: 43.874 21456 - 21456 / com.app.android E / AndroidRuntime: FATAL EXCEPTION: main
Process: com.app.android, PID: 21456
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo {
com.app.android / com.app.android.activity.MainActivity
}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()'
on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java: 2458)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java: 2613)
at android.app.ActivityThread.access$900(ActivityThread.java: 180)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java: 1473)
at android.os.Handler.dispatchMessage(Handler.java: 111)
at android.os.Looper.loop(Looper.java: 207)
at android.app.ActivityThread.main(ActivityThread.java: 5710)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 900)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 761)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()'
on a null object reference
at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java: 117)
at com.app.android.activity.MainActivity. < init > (MainActivity.java: 77)
at java.lang.Class.newInstance(Native Method)
at android.app.Instrumentation.newActivity(Instrumentation.java: 1072)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java: 2448)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java: 2613)
at android.app.ActivityThread.access$900(ActivityThread.java: 180)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java: 1473)
at android.os.Handler.dispatchMessage(Handler.java: 111)
at android.os.Looper.loop(Looper.java: 207)
at android.app.ActivityThread.main(ActivityThread.java: 5710)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 900)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 761)
This is very simple.
You can get context instance after called OnCreate
private AppUpdateHelper appUpdateHelper;
#Override
protected void onCreate(Bundle savedInstanceState) {
appUpdateHelper = new AppUpdateHelper(getApplicationContext());
appUpdateHelper.handleAppUpdate();
}
You can pass the activity context it self using this key word.
#Override
protected void onCreate(Bundle savedInstanceState) {
appUpdateHelper = new AppUpdateHelper(this);
appUpdateHelper.handleAppUpdate();
}
You can't call getApplicationContext() before the class initialized
You can only call after the class initialized. You can get it on onCreate() or other methods called by android.
you are safe to call inside onCreate()
#Override
protected void onCreate(Bundle savedInstanceState) {
appUpdateHelper = new AppUpdateHelper(getActivity()); // if it is Fragment
appUpdateHelper = new AppUpdateHelper(this); // if it is Activity
appUpdateHelper.handleAppUpdate();
}
Application context won't work with Dialog. Because application context does not have theme related information. Use Activity context instead of Application Context
I've been stumped with this problem for two days now. I've checked this forum and other forums but can't get a question or answer close enough to my problem.
Basically I'm trying to execute an intent to open an activity from a non-activities onpostexecute, I'm sending the context (MainActivty.this) and string from a onMarkerClick function that is in a method in the MainActivity. This is going to a constructor in the non-activity which has the parameters for context and the string.
The issue is that I'm getting a null exception, but after debugging, the context is not null, it has the value of MainActivity, but when the intent is executed it returns a null exception. I've also tried many variations eg. Activity, getApplicationContext, this.context, (classname).context, (classname).this and tried a global context to no avail. The odd thing is I put the intent into an if statement if(context != null) and it passes through and it executes the intent which in turn gives me null exception which doesn't make sense. I know I'm new to android if anyone has any other suggestions on opening the activity that would be great thanks very much.
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.quantusapps.joggertest, PID: 12253
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
at android.content.ContextWrapper.getPackageName(ContextWrapper.java:131)
at android.content.ComponentName.(ComponentName.java:77)
at android.content.Intent.(Intent.java:4029)
at com.example.quantusapps.joggertest.BusCoachTramInfo.onPostExecute(BusCoachTramInfo.java:131)
at com.example.quantusapps.joggertest.BusCoachTramInfo.onPostExecute(BusCoachTramInfo.java:25)
at android.os.AsyncTask.finish(AsyncTask.java:632)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:155)
at android.app.ActivityThread.main(ActivityThread.java:5696)
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:1028)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)<
This is the Mainactivity Method with onMarkerClick
mGoogleMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
#Override
public boolean onMarkerClick(Marker marker) {
String bctID = bctExtraMarkerInfo.get(marker.getId());
BusCoachTramInfo busCoachTramInfo = new BusCoachTramInfo(bctID, MainActivity.this);
busCoachTramInfo.execute(bctID);
return false;
}
});
This is the non-activity constructor.
Context context;
BusCoachTramInfo(String busstopID, Context context) {
this.context = context;
naptanIdUrl = "https://api.tfl.gov.uk/StopPoint/" + busstopID + "/Arrivals?app_key=" + tfl_API_KEY + "&app_id=9c0b3009";
}
This is where the null exception is happening.
#Override
protected void onPostExecute(TreeMap<Integer, String[]> Map) {
super.onPostExecute(Map);
Intent i = new Intent(context, BusArrivalTime.class);
context.startActivity(i);
One way to get things done is implementing the AsyncTask as part of a method which takes an instance of MainActivity as a parameter. The AsyncTask on the other hand would work with a WeakReference:
void doExecuteBusCoachTramInfo(final String busstopID, MainActivity activity){
final WeakReference<MainActivity> wrActivity = new WeakReference<MainActivity>(MainActivity.this);
new AsyncTask<Void, Void, TreeMap<Integer, String[]>>(){
#Override
protected TreeMap<Integer, String[]> doInBackground(Void... params)
{
// your code from BusCoachTramInfo here
}
#Override
protected void onPostExecute(TreeMap<Integer, String[]> integerTreeMap)
{
// get back to the original Activity if possible:
MainActivity activity = wrActivity.get();
if (activity != null){
Intent i = new Intent(activity, BusArrivalTime.class);
activity.startActivity(i);
}
}
}.execute();
}
This method may be part of MainActivity, but it can just as well belong to some other class.