null object reference on data binding on runtime-CodePudding

I am using dataBinding

I have MainActivity:

public class MainActivity extends AppCompatActivity {

ActivityMainBinding binding;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    binding = ActivityMainBinding.inflate(getLayoutInflater());
    setContentView(binding.getRoot());
}}

My gradle file:

buildFeatures {
    viewBinding true
    dataBinding true
}

dependencies {
    classpath "com.android.tools.build:gradle:7.0.4"}

I am getting runtime error

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View com.actofit.beat.databinding.ActivityMainBinding.getRoot()' on a null object reference

I can't figure out what is the null object reference, that's what I need help for.

CodePudding user response：

It seems like a problem with your XML structure. Did you check that the root element is a view group (like Relative layout, Constraint layout)?

It should look similar to:

<layout>
    <data>
        ...
    </data>
    <ConstraintLayout>
        ...
    </ConstraintLayout>
</layout>

CodePudding user response：

Try something like this in your onCreate function:

  binding = DataBindingUtil.setContentView(this, R.layout.main_activity);

And also add <layout> </layout> tag in the XML.