Kotin lateinit Var Not initialized - Android Studio

Question

I am working on a simple contact app that stores the contact's name, email, and number. Language: Kotlin Architecture: MVVM But I am getting an error: lateinit property addContactViewModel has not been initialized

Activity:

class AddContact : AppCompatActivity() { private lateinit var addContactViewModel : AddContactViewModel companion object{ const val EXTRA_REPLY = "com.room.contacts.REPLY" } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val binding = DataBindingUtil.setContentView<ActivityAddContactBinding>( this,R.layout.activity_add_contact ) binding.btnSave.setOnClickListener { val replyIntent = Intent() val fname= binding.fnameEdit.text.toString() val lname= binding.lnameEdit.text.toString() val email = binding.emailAddressEdit.text.toString() val contactno = binding.contactNumberEdit.text.toString() val contact = Contact(fname, lname,email,contactno) addContactViewModel.insert(contact) val intent = Intent(this, ContactList::class.java) // start your next activity startActivity(intent) } }}

ViewModel:

class AddContactViewModel (application: Application) : AndroidViewModel(application){ private val repository: ContactRepository init { val contactsDao= ContactRoomDatabase.getDatabase(application).contactDao() repository = ContactRepository(contactsDao) } fun insert(contact: Contact) = viewModelScope.launch { repository.insert(contact) }}

Error:

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.room.contacts, PID: 29383 kotlin.UninitializedPropertyAccessException: lateinit property addContactViewModel has not been initialized at com.room.contacts.screens.addContact.AddContact.access$getAddContactViewModel$p(AddContact.kt:15) at com.room.contacts.screens.addContact.AddContact$onCreate$1.onClick(AddContact.kt:36) at android.view.View.performClick(View.java:4781) at android.view.View$PerformClick.run(View.java:19907) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:160) at android.app.ActivityThread.main(ActivityThread.java:5541) 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:964) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:759)

You should initialize addContactViewModel in oncreate, not in setOnClickListener — MMG
– MMG, Commented Apr 24, 2020 at 17:21
@MohammadMoeinGolchin yes! that makes sense! resolved it like that. Thanks — Haris Bin Saif
– Haris Bin Saif, Commented Apr 24, 2020 at 17:39
Your answer is correct as well. I dig deep into it and seems like the better way to do things is to use the lazy property. Your answer is correct but the other one seems like a better option. — Haris Bin Saif
– Haris Bin Saif, Commented Apr 25, 2020 at 18:50

Michael · Accepted Answer · 2020-04-24 17:32:34Z

3

Instead of having your addContactViewModel as a lateinit property you can make it a lazy property, so that it gets initialized the first time you try to use it somewhere:

class AddContact : AppCompatActivity() { private val addContactViewModel : AddContactViewModel by lazy { ViewModelProvider(this).get(AddContactViewModel::class.java) }

answered Apr 24, 2020 at 17:32

Michael

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2 Comments

Haris Bin Saif Over a year ago

this works too! But rather than instantiating the lateinit var in the listener, I instantiated it in onCreate and that worked for me. This Solution works as well.

Michael Over a year ago

Yeah, both work. But a lazy property has the benefit that you can't forget to initialize it. And you can make it a val, unlike a lateinit property which must be a var.

MMG · Accepted Answer · 2020-04-24 17:40:39Z

0

You should initialize addContactViewModel in oncreate, not in setOnClickListener

answered Apr 24, 2020 at 17:40

MMG

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