我有 MainActivity :

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        System.out.println("MainActivity talking here"); //this works
    }
}

而且， NewActivity :

public class NewActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        System.out.println("NewActivity talking here"); //this doesn't work!
    }
}

为什么不呢 System.out.println("NewActivity talking here"); 工作？