CODEWITHSUNDEEP
androidkotlinandroid-databindingmethod-referenceonlongclicklistener
JJD
JJD

Reputation: 51844

How to write a generic BindingAdapter to setup an OnLongClickListener?

In my Android project I use the following BindingAdapter to wire an OnLongClickListener to views and their corresponding view model.

@JvmStatic
@BindingAdapter(value = ["onLongClick", "onLongClickText"], requireAll = true)
fun setOnLongClickListener(view: View, viewModel: MyViewModel, text: CharSequence) {
    view.setOnLongClickListener {
        viewModel.onButton1LongClick(text)
        true
    }
}

... in the XML layout:

app:onLongClick="@{viewModel}"
app:onLongClickText="@{otherView.text}"

And here is a second adapter in the same view model class:

@JvmStatic
@BindingAdapter("onLongClick")
fun setOnLongClickListener(view: View, viewModel: MyViewModel) {
    view.setOnLongClickListener {
        viewModel.onButton2LongClick()
        true
    }
}

... in the XML layout:

app:onLongClick="@{viewModel}"

I would love to make the BindingAdapter reuseable so it can be wired to different views. I thought I could pass the actual method reference from the XML. Here is my not working draft:

@JvmStatic
@BindingAdapter(value = ["onLongClick", "onLongClickText"], requireAll = true)
fun setOnLongClickListener(view: View, onLongClick: (CharSequence) -> Unit, text: CharSequence) {
    view.setOnLongClickListener {
        onLongClick.invoke(text)
        true
    }
}

... in the XML layout:

app:onLongClick="@{(view) -> viewModel.onButton1LongClick(???)}"
app:onLongClickText="@{otherView.text}"

Upvotes: 1

Views: 358

Answers (1)

Mir Milad Hosseiny
Mir Milad Hosseiny

Reputation: 2857

ViewModel:

class MyViewModel : ViewModel() {

    private val TAG = "MyViewModel"

    fun onButton1LongClick(text: CharSequence) : Unit {
        Log.d(TAG, "onButton1LongClick: " + text)
    }
    val f1 : (CharSequence) -> Unit = {text -> onButton1LongClick(text)}

    fun onButton2LongClick() {
        Log.d(TAG, "onButton2LongClick")
    }
    val f2 : () -> Unit = {onButton2LongClick()}
}

Binding Adapters:

@JvmStatic
@BindingAdapter(value = ["onLongClick", "onLongClickText"], requireAll = true)
fun setOnLongClickListener(view: View, onLongClick: (CharSequence) -> Unit, text: String?) {
    view.setOnLongClickListener {
        onLongClick.invoke(text?:"")
        true
    }
}

@JvmStatic
@BindingAdapter("onLongClick")
fun setOnLongClickListener(view: View, onLongClick: () -> Unit) {
    view.setOnLongClickListener {
        onLongClick.invoke()
        true
    }
}

XML layout:

<EditText
    android:id="@+id/edit_text"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

<Button
    onLongClick="@{viewModel.f1}"
    onLongClickText='@{editText.text.toString()}'
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Button 1" />

<Button
    onLongClick="@{viewModel.f2}"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Button 2" />

Upvotes: 1

Related Questions