lateinit property has not been initialized

Question

I have a custom linearlayout class and when I want to create instance of this class, I get the following error:
lateinit property has not been initialized

I'm using the latest version of butterknife library.

The following is my Kotlin class:

class MenuItemView : LinearLayout {  @BindView(R.id.menu_title_text_view_id) lateinit var menuTitleTextView : CTextBasic  constructor(ctx: Context) : super(ctx) { }  init {     val view = LayoutInflater.from(context).inflate(R.layout.menu_item,this)     ButterKnife.bind(this,view) }  constructor(ctx: Context, attrs: AttributeSet) : super(ctx, attrs) {     val menuAttrs = context.theme.obtainStyledAttributes(attrs, R.styleable.MenuItemView, 0, 0)     try {         val title: String = menuAttrs.getString(R.styleable.MenuItemView_menu_title)         menuTitleTextView.text = title     }catch (e : Exception){         e.printStackTrace()     }finally {         menuAttrs.recycle()     } } fun setTitle( title : String){     menuTitleTextView.text = title } } 

Error Log

kotlin.UninitializedPropertyAccessException: lateinit property menuTitleTextView has not been initialized at com.leavigstone.liberali.ui.custom.menu.MenuItemView.setTitle(MenuItemView.kt:48) at com.leavigstone.liberali.ui.activities.MainActivity.onAddButtonClick(MainActivity.java:142) at com.leavigstone.liberali.ui.activities.MainActivity_ViewBinding$3.doClick(MainActivity_ViewBinding.java:54) at butterknife.internal.DebouncingOnClickListener.onClick(DebouncingOnClickListener.java:22) at android.view.View.performClick(View.java:4780) at android.view.View$PerformClick.run(View.java:19866) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5254) 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:903) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 

Answer 1

If you don't want to use any thirdparty libraries, you can add these extension functions (I tend to have a ContextExtensions.kt or ViewExtensions.kt for Context or View related extension functions), then put in it

inline fun <reified T : View> View.find(id: Int): T = findViewById(id) as T inline fun <reified T : View> Activity.find(id: Int): T = findViewById(id) as T inline fun <reified T : View> Fragment.find(id: Int): T = view?.findViewById(id) as T 

these let you call find from within Activity, Fragment, and Views. So inside your class instead of

@BindView(R.id.menu_title_text_view_id) lateinit var menuTitleTextView : CTextBasic 

you can have

val menuTitleTextView by lazy { find<CTextBasic>(R.id.menu_title_text_view_id) } 

For things like UIs, it's better to val instead of var when they don't need to change. As a general rule in programming, try to keep things as immutable as possible, you would get far less bugs.

Answer 2

I found this works for me.

Change your build.gradle in your project app module.

dependencies {     compile "com.jakewharton:butterknife:8.8.1"     kapt "com.jakewharton:butterknife-compiler:8.8.1" } 

use kapt instead of annotationProcessor.

and then you can do your familiar ButterKnife annotation like this:

class MainActivity : AppCompatActivity() {      @BindView(R.id.myButton)     lateinit var myButton: Button      override fun onCreate(savedInstanceState: Bundle?) {         super.onCreate(savedInstanceState)         setContentView(R.layout.activity_main)         ButterKnife.bind(this)         //...     } } 

Enjoy.