Using DataBinding library for binding events

Solution 1:

I think you will need to bind the handlers as well, maybe something like this in onCreate:

MyHandlers handlers = new MyHandlers();
binding.setHandlers(handlers);

Solution 2:

Many Ways for setting Click

1. Pass handler to binding.

   ActivityMainBinding binding = DataBindingUtil.setContentView(this,R.layout.activity_main); Hander handler = new Handler(); binding.setHandler(handler);

2. Set clicks (use any of below)

   android:onClick="@{handler::onClickMethodReference}"

OR

android:onClick="@{handler.onClickMethodReference}"

OR

android:onClick="@{() -> handler.onClickLamda()}"

OR

android:onClick="@{(v) -> handler.onClickLamdaWithView(v)}"

OR

android:onClick="@{() -> handler.onClickLamdaWithView(model)}"

See Handler class for understanding.

public class Handler {
    public void onClickMethodReference(View view) {
        //
    }
    public void onClickLamda() {
        //
    }
    public void onClickLamdaWithView(View view) {
        //
    }
    public void onClickLamdaWithObject(Model model) {
        //
    }
}

Note that

• You can use Method Reference (::) when you have same argument as the attribute onClick.
• You can pass any object like onClickLamdaWithObject example.
• If you need to pass View object then just use (v)-> expression.

Further reading

https://developer.android.com/topic/libraries/data-binding/expressions

Solution 3:

Use this format in your xml:

android:onClick="@{handlers::onClickFriend}"

Pay attention to the ::, do not worry about the red lines in xml editor, because is currently this is open bug for the Android Studio xml editor.

Where handlers is your variable from data tag:

<data>
    <variable name="handlers" type="com.example.databinding.MyHandlers"/>
</data>

and onClickFriend is your method:

public class MyHandlers {
    public void onClickFriend(View view) {
        Log.i(MyHandlers.class.getSimpleName(),"Now Friend");
    }
}

ADDED

For handle onLongClick in xml add this:

android:onLongClick="@{handlers::onLongClickFriend}"

and add onLongClickFriend method in your ViewModel class:

public class MyHandlers {
    public boolean onLongClickFriend(View view) {
        Log.i(MyHandlers.class.getSimpleName(),"Long clicked Friend");
        return true;
    }
}

ADDED

If you need to show toast message, you can use interface (better variant), or pass context in the MyHandlers class in construction:

public class MyHandlers {
    public boolean onLongClickFriend(View view) {
        Toast.makeText(view.getContext(), "On Long Click Listener", Toast.LENGTH_SHORT).show();
        return true;
    }
}

Solution 4:

If you're going to use your activity, might as well replace the context object that is automatically binded, otherwise you're wasting the space.

A special variable named context is generated for use in binding expressions as needed. The value for context is the Context from the root View's getContext(). The context variable will be overridden by an explicit variable declaration with that name.

binding.setContext(this);

and

<variable name="context" type="com.example.MyActivity"/>

Note if you just use plain string onClick="someFunc" that's not a databinding functionality at all. That's an older feature that uses a little reflection to find the method on the context.