I have a ViewModel that access a List of object of LiveData and i want to assign my variable to that list. Here is the code.
chatViewModel = new ViewModelProvider(this, ViewModelProvider.AndroidViewModelFactory.getInstance(this.getApplication())).get(ChatViewModel.class);
chatViewModel.getAllContactsForChat().observe(this, new Observer<List<UserContacts>>() {
#Override
public void onChanged(List<UserContacts> userContacts) {
Toast.makeText(ChatActivity.this, "inside", Toast.LENGTH_SHORT).show();
for(int i = 0; i<userContacts.size(); i++)
{
UserContacts user = userContacts.get(i);
if(user.getId() == id)
{
firstName = user.getFirstName();
lastName = user.getLastName();
friendPublicKeyString = user.getFriendPublicKey();
profile = user.getPicture();
}
}
}
});
This function is being called in onCreate of the ChatActivity. Now I noticed that the variable firstName, lastName, etc were being given null and my app kept on crashing. Upon debugging further I noticed that when ChatActivity onCreate is called this function is ignored and the main thread goes to next line and after some time it returns to this function and assign values. Now I want it to assign values on the very first run so my app can run normally. Here is the AndroidViewModel code.
public class ChatViewModel extends AndroidViewModel {
private ChatRepository chatRepository;
private LiveData<List<UserContacts>> allContactsForChat;
public ChatViewModel(#NonNull Application application)
{
super(application);
allContactsForChat = chatRepository.getAllContactsForChat();
}
public LiveData<List<UserContacts>> getAllContactsForChat()
{
return allContactsForChat;
}
}
Here is ChatRepository code
public class ChatRepository {
private ChatDao chatDao;
private LiveData<List<UserContacts>> allContactsForChat;
public ChatRepository(Application application)
{
ChatDatabase db = ChatDatabase.getInstance(application);
chatDao = db.chatDao();
allContactsForChat = chatDao.getAllContactsForChat();
}
public LiveData<List<UserContacts>> getAllContactsForChat()
{
return allContactsForChat;
}
}
Here is ChatDao code
#Dao
public interface ChatDao
{
#Query("SELECT * FROM UserContacts")
LiveData<List<UserContacts>> getAllContactsForChat();
}
Here is the crash log. I am converting the profile string to image and profile should be initialized inside onChanged. Since profile is not initialized the function is given null and this error occured.
2021-04-12 11:59:11.440 10151-10151/com.example.privatechatcopy E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.privatechatcopy, PID: 10151
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.privatechatcopy/com.example.privatechatcopy.ChatActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'byte[] java.lang.String.getBytes()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'byte[] java.lang.String.getBytes()' on a null object reference
at android.util.Base64.decode(Base64.java:120)
at com.example.privatechatcopy.NameAndImage.stringToImage(NameAndImage.java:162)
at com.example.privatechatcopy.ChatActivity.onCreate(ChatActivity.java:168)
at android.app.Activity.performCreate(Activity.java:8000)
at android.app.Activity.performCreate(Activity.java:7984)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Related
package com.example.absolutelydumb
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.text.InputType
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import kotlinx.android.synthetic.main.activity_main.*
//sets var to some random number and asks for a guess, giving feedback on proximity to answer
class MainActivity : AppCompatActivity() {
private val startButton: Button = findViewById(R.id.startButton)
private val submitButton: Button = findViewById(R.id.submit)
private val instructionsText: TextView = findViewById(R.id.instructionView)
private val response: EditText = findViewById(R.id.answerInput)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val startText: String = getString(R.string.startText)
startButton.text = startText
//TODO("Add autofillHints")
startButton.setOnClickListener {
numberGuess()
}
//TODO("Set text back to start after guessing is done")
}
fun numberGuess() {
response.inputType = InputType.TYPE_CLASS_NUMBER
val clickText: String = getString(R.string.clickText)
startButton.text = clickText
//TODO("Add autofillHints")
instructionsText.text = getString(R.string.instructions)
val randomNumber: Int = rand(0,10)
submitButton.setOnClickListener {
val responseText = Integer.parseInt(answerInput.text.toString())
if(responseText == randomNumber) {
instructionsText.text = getString(R.string.correctGuess)
} else {
instructionsText.text = getString(R.string.badGuess)
}
}
}
fun rand(start: Int, end: Int): Int {
//require(start <= end) { "Illegal Argument" }
return (start..end).random()
}
}
Above is the code that I've been writing. This is my first project, so I don't know what went wrong. I fixed a variable type problem in the numberGuess function but when I finished fixing it the app wouldn't open and the virtual device stated a "app keeps stopping" error.
Here is the Run log that lists off errors. The build log didn't have any errors.
07/09 19:58:05: Launching 'app' on phone1.
Install successfully finished in 1 s 266 ms.
$ adb shell am start -n "com.example.absolutelydumb/com.example.absolutelydumb.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Connected to process 5935 on device 'phone1 [emulator-5554]'.
Capturing and displaying logcat messages from application. This behavior can be disabled in the "Logcat output" section of the "Debugger" settings page.
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.absolutelydumb, PID: 5935
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.absolutelydumb/com.example.absolutelydumb.MainActivity}: 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:2843)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
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:159)
at android.view.ContextThemeWrapper.getTheme(ContextThemeWrapper.java:157)
at android.content.Context.obtainStyledAttributes(Context.java:675)
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.absolutelydumb.MainActivity.<init>(MainActivity.kt:13)
at java.lang.Class.newInstance(Native Method)
at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:69)
at androidx.core.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:45)
at android.app.Instrumentation.newActivity(Instrumentation.java:1215)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2831)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
You cannot call findViewById before onCreate() or setContentView() is called. Since you are using findViewById at the declaration site of your four properties, it is being called at the time your Activity class is being instantiated, which is before onCreate is called.
There are two ways to handle this.
Use lateinit var and set the properties right after your call to setContentView():
private lateinit var startButton: Button
//...
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
button = findViewById(R.id.startButton)
//...
Use by lazy so it is only called when the property is first accessed, which will be after setContentView() is called:
private val startButton: Button by lazy { findViewById(R.id.startButton) }
Or you can use view binding, which gets rid of most of this boilerplate and is less error-prone. By error-prone, I mean you can call findViewById and accidentally search for a view that isn't present in the current layout and it will crash at runtime. View binding makes this impossible.
I have an instrumented test that starts an application with a content provider.
The test is straightforward:
#HiltAndroidTest
#UninstallModules({...})
public class MyTest {
#Rule
public HiltAndroidRule hiltRule = new HiltAndroidRule(this);
#Test
...
}
However, the application under test includes a ContentProvider, and this provider is using Hilt to inject data:
public class MyProvider extends ContentProvider {
#EntryPoint
#InstallIn(ApplicationComponent.class)
interface MyProviderEntryPoint {
#SqliteDatabaseName String databaseName();
}
#Override
synchronized public boolean onCreate() {
Context appContext = getContext().getApplicationContext();
MyProviderEntryPoint entryPoint =
EntryPointAccessors.fromApplication(appContext, MyProviderEntryPoint.class);
mOpenHelper = new SqliteStoreOpener(getContext(), entryPoint.databaseName());
return true;
}
This causes the test to crash on startup:
java.lang.RuntimeException: Unable to get provider com.test.MyProvider: java.lang.IllegalStateException: The component was not created. Check that you have added the HiltAndroidRule.
at android.app.ActivityThread.installProvider(ActivityThread.java:6242)
at android.app.ActivityThread.installContentProviders(ActivityThread.java:5805)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5722)
at android.app.ActivityThread.-wrap1(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1656)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.IllegalStateException: The component was not created. Check that you have added the HiltAndroidRule.
at dagger.hilt.internal.Preconditions.checkState(Preconditions.java:83)
at dagger.hilt.android.internal.testing.TestApplicationComponentManager.generatedComponent(TestApplicationComponentManager.java:79)
at dagger.hilt.android.testing.HiltTestApplication.generatedComponent(HiltTestApplication.java:49)
at dagger.hilt.EntryPoints.get(EntryPoints.java:46)
at dagger.hilt.android.EntryPointAccessors.fromApplication(EntryPointAccessors.java:36)
at com.test.MyProvider.onCreate(EboBirthdayProvider.java:114)
at android.content.ContentProvider.attachInfo(ContentProvider.java:1917)
at android.content.ContentProvider.attachInfo(ContentProvider.java:1892)
at android.app.ActivityThread.installProvider(ActivityThread.java:6239)
at android.app.ActivityThread.installContentProviders(ActivityThread.java:5805)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5722)
at android.app.ActivityThread.-wrap1(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1656)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
I suppose the problem is that the framework is trying to install the provider before Hilt even had a chance to start up and create the components. What's the proper setup to allow Hilt to run first and then construct the providers? For reference, I have a simple test runner:
public class MyRunner extends AndroidJUnitRunner {
#Override
public Application newApplication(ClassLoader cl, String className, Context context)
throws InstantiationException, IllegalAccessException, ClassNotFoundException {
return super.newApplication(cl, HiltTestApplication.class.getName(), context);
}
This is very anti-climactic, but it ended up being a problem in the build.gradle file.
The annotation processor was added as
annotationProcessor 'com.google.dagger:hilt-android-compiler:2.30.1-alpha'
instead of
androidTestAnnotationProcessor 'com.google.dagger:hilt-android-compiler:2.30.1-alpha'
private fun setupGeckoView() {
val runtime = GeckoRuntime.create(this) // crashes on this line
geckoSession.open(runtime)
geckoView.setSession(geckoSession)
val url = String(Base64.decode(MYURL, Base64.DEFAULT))
geckoSession.loadUri(url)
geckoSession.progressDelegate = createProgressDelegate()
geckoSession.settings.allowJavascript = true
}
i call setUpGeckoView methon in onCreat() but when i click back and
reopen the app then app crashes with IllegalStateException saying
"Failed to initialize GeckoRuntime. It works first time only crashed when i click back and then open app again"
Logs are given below
Process: arholding.kargoshop.mk, PID: 16444
java.lang.RuntimeException: Unable to start activity ComponentInfo{arholding.kargoshop.mk/arholding.kargoshop.mk.SeckoActivity}: java.lang.IllegalStateException: Failed to initialize GeckoRuntime
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3447)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3594)
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$H.handleMessage(ActivityThread.java:2146)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:237)
at android.app.ActivityThread.main(ActivityThread.java:7762)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1047)
Caused by: java.lang.IllegalStateException: Failed to initialize GeckoRuntime
at org.mozilla.geckoview.GeckoRuntime.create(GeckoRuntime.java:458)
at org.mozilla.geckoview.GeckoRuntime.create(GeckoRuntime.java:333)
at arholding.kargoshop.mk.SeckoActivity.setupGeckoView(SeckoActivity.kt:23)
at arholding.kargoshop.mk.SeckoActivity.onCreate(SeckoActivity.kt:19)
at android.app.Activity.performCreate(Activity.java:7981)
at android.app.Activity.performCreate(Activity.java:7970)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
This exception will be thrown if there is already an active Gecko instance running. There are many ways to resolve this problem.
Solution 1: Get the default runtime for the given context.
Change your code from
val runtime = GeckoRuntime.create(this)
to
val runtime = GeckoRuntime.getDefault(this)
Solution 2: Kill the process when exit app by finishing activity, add this code into your activity.
override fun onDestroy() {
Process.killProcess(Process.myPid())
super.onDestroy()
}
Solution 3: Only create a new instance if there is no active instance running
private fun setupGeckoView() {
if (geckoRuntime == null) {
geckoRuntime = GeckoRuntime.create(this)
}
geckoSession.open(geckoRuntime!!)
geckoView.setSession(geckoSession)
val url = String(Base64.decode(MYURL, Base64.DEFAULT))
geckoSession.loadUri(url)
geckoSession.progressDelegate = createProgressDelegate()
geckoSession.settings.allowJavascript = true
}
companion object {
var geckoRuntime: GeckoRuntime? = null
}
SO I am trying to observe some LiveData in my repository, so I can work with this data and update it's items according to my operations. But I can't figure out how to access the data. When I try to observe it, the ~Observeris asking for a LifecycleOwner. Reading about similar problems I've seen a suggestion to extendLifecycleService, but when I do I get the error sayingOnly one class may appear in a supertype list`.
How do I go around this?
This is my service:
class DetectJobIntentService : JobIntentService() {
private val TAG = "DetectJobIntentServi22"
fun enqueueWork(context: Context, work: Intent) {
enqueueWork(context, DetectJobIntentService::class.java, 12, work)
}
override fun onHandleWork(intent: Intent) {
Log.d(TAG, "onHandleWork")
val options = FirebaseVisionFaceDetectorOptions.Builder()
.setClassificationMode(FirebaseVisionFaceDetectorOptions.ACCURATE)
.setClassificationMode(FirebaseVisionFaceDetectorOptions.ALL_CLASSIFICATIONS)
.setMinFaceSize(0.15f)
.build()
val detector = FirebaseVision.getInstance()
.getVisionFaceDetector(options)
val repo = PhotoRepository(application)
val allPhotos = repo.getAllPhotos()
allPhotos.observe(SomeLifeCycleOwner, Observer {
for (file in it) {
val image = FirebaseVisionImage.fromFilePath(application, Uri.parse(file.uri))
detector.detectInImage(image).addOnSuccessListener { list ->
if (list.isNotEmpty()) {
file.hasFaces = 1
repo.update(file)
} else {
file.hasFaces = 2
repo.update(file)
}
}
}
})
}
}
EDIT: Following Sina's suggestion which sounds right, I've tried implementing a query that fetches the data into a non-LiveData object my app crashes.
This is the quesry I've added in my Dow:
#Query("SELECT * FROM photos_table")
fun getAllPhotosStatic(): MutableList<Photo>
If I run at at this point it's all good.
Then in my repository I've added this:
val allPhotosStatic = photoDao.getAllPhotosStatic()
And as soon as I've done that and try to run the app it crashes, and I get this stack:
2019-11-13 23:49:37.079 20720-20720/tech.levanter.anyvision E/AndroidRuntime: FATAL EXCEPTION: main
Process: tech.levanter.anyvision, PID: 20720
java.lang.RuntimeException: Unable to start activity ComponentInfo{tech.levanter.anyvision/tech.levanter.anyvision.MainActivity}: java.lang.RuntimeException: Cannot create an instance of class tech.levanter.anyvision.viewModels.AllPhotosViewModel
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2991)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3126)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1846)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6882)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)
Caused by: java.lang.RuntimeException: Cannot create an instance of class tech.levanter.anyvision.viewModels.AllPhotosViewModel
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:238)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:164)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:130)
at tech.levanter.anyvision.MainActivity.onCreate(MainActivity.kt:66)
at android.app.Activity.performCreate(Activity.java:7232)
at android.app.Activity.performCreate(Activity.java:7221)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1272)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2971)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3126)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1846)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6882)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:343)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:230)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:164)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:130)
at tech.levanter.anyvision.MainActivity.onCreate(MainActivity.kt:66)
at android.app.Activity.performCreate(Activity.java:7232)
at android.app.Activity.performCreate(Activity.java:7221)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1272)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2971)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3126)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1846)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6882)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)
Caused by: java.lang.IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long period of time.
at androidx.room.RoomDatabase.assertNotMainThread(RoomDatabase.java:267)
at androidx.room.RoomDatabase.query(RoomDatabase.java:323)
at androidx.room.util.DBUtil.query(DBUtil.java:83)
at tech.levanter.anyvision.room.PhotoDao_Impl.getAllPhotosStatic(PhotoDao_Impl.java:154)
at tech.levanter.anyvision.room.PhotoRepository.<init>(PhotoRepository.kt:37)
at tech.levanter.anyvision.viewModels.AllPhotosViewModel.<init>(AllPhotosViewModel.kt:12)
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:343)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:230)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:164)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:130)
at tech.levanter.anyvision.MainActivity.onCreate(MainActivity.kt:66)
at android.app.Activity.performCreate(Activity.java:7232)
at android.app.Activity.performCreate(Activity.java:7221)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1272)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2971)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3126)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1846)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6882)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)
I thought maybe I can just get a copy of the data into a static list in my repository, but for that I'd need to observe it in the repository and I'm stuck at the same place again because I don't have a lifecycleOwner.
The idea in MVVM is to observe from view if you are doing an action that you want to be sure is finished do not wrap it in a livedata. Basically you don't need any life cycle aware component. Your query should return list of photos without any need to observe it. I mean in your dao if you don't wrap data in a livedata you don't need to observe anything and getAllPhotos return photos. You can do this kind of thing anywhrere just do everything from background, in a thread or something. For both kind of designs you can have 1 livedata wraped method in dao and 1 method without livedata for jobs that need to be done serially.
Update: put your code in a background thread:
new Thread(new Runnable() {
#Override
public void run() {
val allPhotosStatic = photoDao.getAllPhotosStatic()
for (file in it) {
val image = FirebaseVisionImage.fromFilePath(application, Uri.parse(file.uri))
detector.detectInImage(image).addOnSuccessListener { list ->
if (list.isNotEmpty()) {
file.hasFaces = 1
repo.update(file)
} else {
file.hasFaces = 2
repo.update(file)
}
}
}
}
}).start();
or:
AsyncTask.execute(new Runnable() {
#Override
public void run() {
val allPhotosStatic = photoDao.getAllPhotosStatic()
for (file in it) {
val image = FirebaseVisionImage.fromFilePath(application, Uri.parse(file.uri))
detector.detectInImage(image).addOnSuccessListener { list ->
if (list.isNotEmpty()) {
file.hasFaces = 1
repo.update(file)
} else {
file.hasFaces = 2
repo.update(file)
}
}
}
}
});
I'm trying to run an app adopting MVVM pattern architecture, but I'm getting an exception that I can't solve.
I have my MainActivity.java which has an observe to the firstTime() method in the MainViewModel.java.
MainActivity.java
(...)
ViewModelProvider.Factory mViewModelFactory;
ActivityMainBinding mActivityStartBinding;
private MainViewModel mainViewModel;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mActivityStartBinding = getViewDataBinding();
mainViewModel.firstTime().observe(this, new Observer<Boolean>() {
#Override
public void onChanged(#Nullable Boolean aBoolean) {
if(aBoolean !=null && aBoolean){
mainViewModel.setisFirstRun();
}
}
});
MainViewModel.java
(...)
private final DataManager mDataManager; <--- repository
public LiveData<Boolean> firstTime(){
if(mDataManager.isFirstRun())
{
Timber.d("-------------- Is first read from database ");
return mDataManager.saveValues();
}
else
{
Timber.d("-------------- Is not first read from database ");
return null;
}
}
And every time I run I get the following Exception that I can't resolve.
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rd.ch/com.rd.ch.ui.main.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.arch.lifecycle.LiveData.observe(android.arch.lifecycle.LifecycleOwner, android.arch.lifecycle.Observer)' 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 'void android.arch.lifecycle.LiveData.observe(android.arch.lifecycle.LifecycleOwner, android.arch.lifecycle.Observer)' on a null object reference
at com.rd.ch.ui.main.MainActivity.onCreate(MainActivity.java:55)
at android.app.Activity.performCreate(Activity.java:6251)
How can I solve this?
The reason of getting NPE is that you have missed to initialize your viewModel object in activity onCreate.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mainViewModel = ViewModelProviders.of(this).get(MainViewModel.class);
// Rest of the code
}