App Crash when trying to list item from hilt and dagger-CodePudding

I am new to android development. My app crash when I am trying to list items from hilt generation. I can't figure the problem. It would be nice if anyone can help me out. Many thanks.

AppModule

@Module
@InstallIn(SingletonComponent::class)
object AppModule {

    @Provides
    fun provideTestString() = "This is a string we will inject"

    @Provides
    @Singleton
    fun provideDatabase(
        app: Application,
        callback: LanguageDatabase.Callback
    ) = Room.databaseBuilder(app, LanguageDatabase::class.java, "language_database")
        .fallbackToDestructiveMigration()
        .addCallback(callback)
        .build()

    @Provides
    fun provideLanguageDao(db: LanguageDatabase) = db.languageDao()

    @ApplicationScope
    @Provides
    @Singleton
    fun provideApplicationScope() =  CoroutineScope(SupervisorJob())

}

@Retention(AnnotationRetention.RUNTIME)
@Qualifier
annotation class ApplicationScope

Language

 @Entity(tableName = "language_table")
    data class Language(
        val isChecked: Boolean,
        val language: String,
        @PrimaryKey(autoGenerate = true) val id: Int = 0
    )

Language Adapter

class LanguageAdapter(private val language: List<Language>) :
    RecyclerView.Adapter<LanguageAdapter.ViewHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val view =
            LayoutInflater.from(parent.context).inflate(R.layout.item_language, parent, false)
        return ViewHolder(view)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.bind(language[position])
    }

    override fun getItemCount(): Int = language.size

    class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        fun bind(index: Language) {

            itemView.findViewById<CheckBox>(R.id.isChecked).isChecked = index.isChecked
            itemView.findViewById<TextView>(R.id.language).text = index.language

        }
    }
    
}

LanguageDao

@Dao
interface LanguageDao {

    @Query("SELECT * FROM language_table")
    fun getLanguage(): Flow<List<Language>>

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    suspend fun insert(language: Language)

    @Update
    suspend fun update(language: Language)

    @Delete
    suspend fun delete(language: Language)
}

Language Database

@Database(entities = [Language::class], version = 3)
abstract class LanguageDatabase: RoomDatabase() {

    abstract fun languageDao(): LanguageDao

    class Callback @Inject constructor(
        private val database: Provider<LanguageDatabase>,
        @ApplicationScope private val applicationScope: CoroutineScope
    ): RoomDatabase.Callback(){
        override fun onCreate(db: SupportSQLiteDatabase) {
            super.onCreate(db)

            // db operation
            val dao = database.get().languageDao()

            applicationScope.launch {
                dao.insert(Language(true, "English"))
                dao.insert(Language(true, "Spanish"))
                dao.insert(Language(false, "Russian"))
                dao.insert(Language(true, "Japanese"))
                dao.insert(Language(true, "Korean"))
                dao.insert(Language(true, "Hindi"))
                dao.insert(Language(true, "Chinese"))
                dao.insert(Language(true, "Italian"))
                dao.insert(Language(true, "Arabic"))
                dao.insert(Language(true, "German"))

            }

        }
    }

}

Language Fragment

@AndroidEntryPoint
class LanguageFragment: Fragment(R.layout.language_fragment){

    private lateinit var binding: LanguageFragmentBinding
    private lateinit var languageList: RecyclerView

    @Inject
    lateinit var testString: String

    private val viewModel: LanguageViewModel by viewModels()

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.language_fragment, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        languageList = binding.languageList
        languageList.layoutManager = LinearLayoutManager(context)

        observeLanguage()

    }



    private fun observeLanguage() {
        viewModel.languages.observe(viewLifecycleOwner) {
            languageList.adapter = LanguageAdapter(it)
        }
    }

}

Language View Model

@HiltViewModel
class LanguageViewModel @Inject constructor(
    private val languageDao: LanguageDao
) : ViewModel() {

    val languages = languageDao.getLanguage().asLiveData()

}

Main Activity

@AndroidEntryPoint
class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        replacementFragment(HomeFragment())

        binding.bottomNavigationView.setOnItemSelectedListener{
            when(it.itemId){
                R.id.home -> replacementFragment(HomeFragment())
                R.id.language -> replacementFragment(LanguageFragment())
            }
            true
        }
    }

    private fun replacementFragment(fragment: Fragment){

        val fragmentManager = supportFragmentManager
        val fragmentTransaction = fragmentManager.beginTransaction()
        fragmentTransaction.replace(R.id.fragmentContainerView, fragment)
        fragmentTransaction.commit()
    }
}

MyApplication

@HiltAndroidApp
class MyApplication : Application(){
}

Activity Main

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.fragment.app.FragmentContainerView
        android:id="@ id/fragmentContainerView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toTopOf="@ id/bottomNavigationView"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />


    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@ id/bottomNavigationView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toBottomOf="@ id/fragmentContainerView"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:menu="@menu/bottom_nav"/>

</androidx.constraintlayout.widget.ConstraintLayout>

Item Language

    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">
    
        <CheckBox
            android:id="@ id/isChecked"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentStart="true"
            android:minWidth="48dp"
            android:minHeight="48dp" />
    
        <TextView
            android:id="@ id/language"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignTop="@ id/isChecked"
            android:layout_alignBottom="@ id/isChecked"
            android:layout_toEndOf="@ id/isChecked"
            android:ellipsize="end"
            android:gravity="center_vertical"
            android:maxLines="1"
            tools:text="English" />
    
    
    </RelativeLayout>

Language fragment

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    tools:context=".LanguageFragment">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@ id/language_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />


</LinearLayout>

Error Message

2022-08-01 22:16:51.818 17977-17977/? E/Zygote: accessInfo : 1
2022-08-01 22:16:51.853 17977-17977/? E/le.testfragmen: Unknown bits set in runtime_flags: 0x8000
2022-08-01 22:16:55.810 17977-17977/com.example.testfragment E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.testfragment, PID: 17977
    kotlin.UninitializedPropertyAccessException: lateinit property binding has not been initialized
        at com.example.testfragment.LanguageFragment.onViewCreated(LanguageFragment.kt:37)
        at androidx.fragment.app.Fragment.performViewCreated(Fragment.java:3019)
        at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:551)
        at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:261)
        at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1840)
        at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1758)
        at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1701)
        at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:488)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:237)
        at android.app.ActivityThread.main(ActivityThread.java:8167)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:496)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1100)

CodePudding user response：

Use databinding or viewbinding as per your requirement

 private var _binding: LanguageFragmentBinding? = null
    // This property is only valid between onCreateView and
    // onDestroyView.
    private val binding get() = _binding!!
    
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        _binding = LanguageFragmentBinding.inflate(inflater, container, false)//Here is need to change. 
        val view = binding.root
        return view
    }
    
    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }

CodePudding user response：

override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.language_fragment, container, false) // this is wrong
    }

you need to use binding ..either viewbinding or databinding

Databinding

CodePudding user response：

You are using lateinit property which is binding has not been initialized.

You are intialize in

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        languageList = binding.languageList // here
        languageList.layoutManager = LinearLayoutManager(context)

        observeLanguage()

    }

which is not intialize. so you have intialize as like

private lateint val languageList: RecyclerView? = binding?.languageList
intialize languageList in onCreateView