Android - Create custom xml attributes like onClick?

Question

I am trying to create a custom view which contains two buttons say OK and Cancel. I have two methods in my view model say fun onOkClicked(view View) and fun onCancelClicked(view View). How can I pass these functions through XML layout file like android:onClick="methodName"where we can pass a function from a context from activity or view model so the passed method get called when these buttons clicked. Is it possible to create custom attributes like onCreate ? I am aware of creating custom attributes but I am stuck in getting and invoking the functions that passed from the context.

Did you try this way? https://stackoverflow.com/questions/44150912/android-viewmodel-livedata-update-view-on-button-click — Manikandan K, Dec 13 '19 at 09:28
You could have a look at how it's done in `View`: https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/view/View.java#6094. Basically, after you get the method name from the attributes, you instantiate a `DeclaredOnClickListener` with it, and set that as the `OnClickListener` on your inner `Button`. — Mike M., Dec 13 '19 at 09:38

score 0 · Answer 1 · answered Dec 16 '19 at 05:19

As you using the viewmodel, so might aware about the databinding, it can help you to pass viewmodel into xml.

Little guidance of DataBinding just in case

Now you custom view xml should look like this from top

 <?xml version="1.0" encoding="utf-8"?>
    <layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto">

        <data>
            <variable
                name="viewModel"
                type="com.samples.LoginViewModel" />
        </data>
      <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"
        android:orientation="vertical"
        android:padding="20dp">
        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="8dp"
            tools:fontPath=""
            android:onClick="@{(v) -> viewModel.onOkClicked()}"
            android:text="Ok" />

        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="8dp"
            android:onClick="@{(v) -> viewModel.onCancelClicked()}"
            android:text="Cancel" />

    </LinearLayout>

</layout>

and in your data class, you can use it like below.

let say your xml name : custom_view.xml

So, in your Fragment/Activity/View

val binding: CustomViewBinding = CustomViewBinding.inflate(inflater, container, false)
binding.lifecycleOwner = viewLifecycleOwner
binding.viewModel = viewModel
binding.executePendingBindings()

Let me know if that helps.

Android - Create custom xml attributes like onClick?

1 Answers1