ViewBinding with dynamically added content

Question

I have base activity implementing some features for every screen of my app. Every child activity then overrides method with its XML layout.

BaseActivity

@Override
protected void onCreate(Bundle savedInstanceState) {
    setContentView(R.layout.base_screen);
    View mFormView = findViewById(R.id.pnContent);
    if (getContentAreaLayoutId() != 0) {
        LayoutInflater inflater = LayoutInflater.from(this);
        View contentLayout = inflater.inflate(getContentAreaLayoutId(), (ViewGroup) mFormView, false);
        ((ViewGroup) mFormView).addView(contentLayout, 0);
    }
}

ChildActivity

override fun getContentAreaLayoutId(): Int = R.layout.standard_content_settings

Now I would like to use view binding in my child activities. I was thinking about something like this:

override fun onCreate(savedInstanceState: Bundle?) {
    val binding = StandardContentSettingsBinding.inflate(layoutInflater)
}

But when I used binding (binding.edURL.setText("test")), view does not change and stays empty. I guess I'm using view binding wrong and have to inflate it with another way?

Answer 1

You can inflate the binding object in the BaseActivity and expose methods to child activities to get the binding object.

public abstract class BaseActivity extends AppCompatActivity {

    //base binding
    private BaseScreenBinding baseBinding;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); // always call base methods, your code didnt have those calls.

        baseBinding = BaseScreenBinding.inflate(getLayoutInflater());
        setContentView(baseBinding.getRoot());

        //your existing code to inflate child content
        View mFormView = baseBinding.pnContent;
        if (getContentAreaLayoutId() != 0) {
            LayoutInflater inflater = LayoutInflater.from(this);
            View contentLayout = inflater.inflate(getContentAreaLayoutId(), (ViewGroup) mFormView, false);
            ((ViewGroup) mFormView).addView(contentLayout, 0);
        }
    }
    
    protected BaseScreenBinding getBaseBinding() {
        return baseBinding;
    }

    protected abstract int getContentAreaLayoutId();
}

you can now use ViewBinding in your child activity, your layout was inflated by BaseActivity, in child you will bind to it.

class ChildActivity : BaseActivity() {

    private lateinit var binding: StandardContentSettingsBinding

    override fun getContentAreaLayoutId(): Int = R.layout.standard_content_settings

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // Layout was inflated in BaseActivity, so now only bind to it.
        binding = StandardContentSettingsBinding.bind(getBaseBinding().pnContent)

        //This should work now
        binding.edURL.setText("test")
    }
}

In the child activity, calling StandardContentSettingsBinding.bind(View), is different from inflate(), as it doesn't create a new view hierarchy but instead uses the existing one, which is what you want in this case.

some references: https://developer.android.com/topic/libraries/data-binding/generated-binding