Set activity theme based on card category

setTheme.java

public class CardDetailActivity extends AppCompatActivity {
  
  public static final String EXTRA_CARD = "card";
  
  @Override 
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    
    Card card = getIntent().getParcelableExtra(EXTRA_CARD);
    setTheme(card.category.getThemeId());
    
    // inflate views
    // ...
  }
}