Things after Kotlin Android Extensions(KTX)
I remembered in MVVM when I have to declare ViewModel, I initialize View Model like this.
private val viewModel: MainViewModel by lazy {
ViewModelProvider(this).get(MainViewModel::class.java)
}but now using KTX it becomes
//when you need fragment scope
private val viewModel: MainViewModel by viewModels()
//when you need activity scope
private val viewModel: MainViewModel by activityViewModels()
And when I have to declare RecyclerView View Holder, then either I use normal findByViewId() or Databinding
class RecyclerVH(private val binding: ItemXBinding) : RecyclerView.ViewHolder(binding.root) {
fun bind(dataB: DataB) {
binding.tvNote.text = dataB.note
}
}
but after KTX View Holder become
class RecyclerVH(private val view: View) : RecyclerView.ViewHolder(view),LayoutContainer {
override val containerView: View?
get() = view
fun bind(dataB: DataB) {
tv_note.text = dataB.note
}
}
And same activity, fragment or custom view, when you inflate then you have to initialize data binding
in Fragment
lateint var binding:MyviewFragmentBinding
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
binding=inflater.inflate(R.layout.myview_fragment, container, false))
return binding.root!!
}
//To access view
binding.tvNote.text="Hello Binding"
in Activity
private val binding: ActivityMyviewBinding by lazy {
DataBindingUtil.setContentView>(this, R.layout.activity_myview)
}
//To access view
binding.tvNote.text="Hello Binding"
But after KTX, Just access view id directly, more elegant code no more binding
tv_note.text="Hello DataBinding"
And for Custom View before KTX
class MyView @JvmOverloads constructor(
context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : FrameLayout(context, attrs, defStyleAttr), View.OnClickListener {
val binding = MyViewBinding.inflate(LayoutInflater.from(context), this, true)
init{
binding.tvNote.text="Hello binding"
}
}
And after KTX it becomes
class MyView @JvmOverloads constructor(
context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : FrameLayout(context, attrs, defStyleAttr), View.OnClickListener {
init{
MyViewBinding.inflate(LayoutInflater.from(context), this, true)
tv_note.text="Hello binding"
}
}
or use LayoutContainer
class MyView @JvmOverloads constructor(
context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : FrameLayout(context, attrs, defStyleAttr), View.OnClickListener, LayoutContainer {
private val view = LayoutInflater.from(context).inflate(R.layout.myview, this, true)
override val containerView: View?
get() = view
init{
tv_note.text="Hello LayoutContainer"
}
}
Kotlin Android extension libraries or plugin which I have used for above sample codes
//For LayoutContainer and access view id directly.
apply plugin: 'kotlin-android-extensions' //in app build.gradle
//in android{} block
androidExtensions {
experimental = true
}
//for viewModels and activityViewModels
androidx.fragment:fragment-ktx:$version
