如何编写通用的BindingAdapter来设置OnLongClickListener？

Question

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在我的Android项目中，我使用以下BindingAdapter将OnLongClickListener连接到视图及其对应的视图模型。

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

...在XML布局中：

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

这是同一视图模型类中的第二个适配器：

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

...在XML布局中：

app:onLongClick="@{viewModel}"

我想制作BindingAdapter 可重用，以便可以将其连接到不同的视图。我以为我可以通过XML传递实际的方法引用。这是我的不工作草稿：

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

...在XML布局中：

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

Answer 1

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()}
}

绑定适配器：

@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布局：

<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" />