Unable to launch another activity from fragment in android studio

I have a fragment in which I am trying to call a new activity on a button click.

 btnLoadLimit.setOnClickListener(v -> {
        Intent intent = new Intent(getActivity(), DataActivity.class);
        startActivity(intent);
    });

Data Activity

public class DataActivity extends AppCompatActivity {
 Context mContext;

 @BindView(R.id.smart_msn_spinner)
Spinner msnSpinner;

 ArrayList<String> msnArrayList = new ArrayList<>(Arrays.asList("Select MSN","002998002010" )); //"002999002020"

ArrayAdapter<String> msnAdapter;

 @Override
 protected void onCreate(Bundle savedInstanceState) {


  msnAdapter = new ArrayAdapter<>(mContext, android.R.layout.simple_spinner_dropdown_item, msnArrayList);
    msnSpinner.setAdapter(msnAdapter);
    msnSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            selectedMeterNo = msnArrayList.get(position);
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {

        }
    });
        
 }

}

When I click on btnLoadLimit button my app is closing with the following error

> Unable to start activity ComponentInfo{com.thumbsol.accuratemobileassetsmanagament/com.thumbsol.accuratemobileassetsmanagament.fragment.DataActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference
>
> at com.thumbsol.accuratemobileassetsmanagament.fragment.DataActivity.onCreate(DataActivity.java:122)

The line 122 is msnAdapter = new ArrayAdapter<>(mContext, android.R.layout.simple_spinner_dropdown_item, msnArrayList);

The same method I have applied in my fragment and it's working but in my new activity it's not.

Note: The activity is displaying if none of the methods are invoked.

Looks like you don't initialize your mContext. meaning you're passing null to your ArrayAdapter().

You shouldn't be storing your context anyway, since your context is your activity..
You can just use this:

msnAdapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, msnArrayList);