Replacement for onClick event in xml tag via Databinding

Question

My question is simple but I can't seem to do what I want to.

So In my activity I have this method.

 public void performButtonClick(View view)
 {
        Log.i("INTRO", "OK");
 }

Which is called from a button click event defined in xml like so

 <Button

               android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:onClick="performButtonClick"
                android:text="@string/start"/>

Now I've heard that this approach is using reflection which slows down performance so I'm trying to replace the onClick event with databinding.

I tried various combinations like

android:onClick="@{performButtonClick}"

or

 android:onClick="@{(v) -> performButtonClick(v)}"

or

android:onClick="@{(v) -> MainActivity::performButtonClick}"

but None of these worked.
Could you help me out?

Answer 1

Ok answering to my own question.

I am new to DataBinding but I do not understand why I have to use copy-pasted solutions which make use of an accessory Handlers class and end up with more boilerplate code than I used to have.

All I wanted is an equivalent to android:onClick="performButtonClick" So here is my solution:

activity_main.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>

        <variable
            name="activity"
            type="com.example.mydatabinding.MainActivity"/>
    </data>

<LinearLayout
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/bg"
        android:orientation="vertical">

<Button
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:onClick="@{activity::performButtonClick}"
                android:text="@string/start"/>
</LinearLayout>

MainActivity.java

public final class MainActivity extends AppCompatActivity
{
    ActivityMainBinding binding;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        binding.setActivity(this);
    }

    public void performButtonClick(View view)
    {
        Log.i("INTRO", "OK");
    }
}