Android development hidden title bar problem

The first way:

requestWindowFeature(Window.FEATURE_NO_TITLE);

Note that this method is useless when the inherited class is AppCompatActivity, as follows, change it to Activity

public class MainActivity extends AppCompatActivity

The correct spelling is:

public class MainActivity extends Activity {                 //继承 Activity
       // ...
       
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate (savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE); //Write in front of the setContentView() function
        setContentView(R.layout.activity_listview);
        //...
    }

The second way:

getSupportActionBar().hide();

The inherited class is AppCompatActivity, as follows

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate (savedInstanceState);
        setContentView(R.layout.activity_listview);
        getSupportActionBar().hide(); //Write after the setContentView() function
       //...
    }

For beginners, write this note.