Android ListView with Checkbox : Unknown string is displayed

I would like to develop a ListView with Checkbox. However, an unknown character string is displayed.[1]

What is this string? Why is this character string displayed?

Main:

public class MainActivity extends AppCompatActivity {

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

        ListView lvCB = findViewById(R.id.lvCB);

        List<Object> cbList = new ArrayList<>();
        cbList.add(MainActivity.this);

        ArrayAdapter<Object> adapter = new ArrayAdapter<>(MainActivity.this, R.layout.row, cbList);
        lvCB.setAdapter(adapter);
    }
}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<ListView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/lvCB"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

row.xml

<?xml version="1.0" encoding="utf-8"?>

<CheckBox xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/cb01"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text=""/>