How to change title of Activity in Android?

Try setTitle by itself, like this:

setTitle("Hello StackOverflow");

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.Main_Activity);
    this.setTitle("Title name");
}

The code helped me change the title.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_name);
    ActivityName.this.setTitle("Your Activity Title");}

Inside a MainActivity:

public class act1 extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.act1);

    setTitle("First Activity");

}

}

setTitle("Whatever apps"); in MainActivity.java is simplier I would say.

In Kotlin, this way:

this.title = resources.getText(R.string.fast_learning)

If you're using onCreateOptionsMenu, you can also add setTitle code in onCreateOptionsMenu.

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);

    setTitle("Neue Aktivität");
    return true;
}

setTitle("Welcome Activity");