public class Time {
    private MutableLiveData<Integer> seconds = new MutableLiveData<>();
    public MutableLiveData<Integer> getSeconds() {
        return seconds;
    }
}

public class TestViewModel extends ViewModel {
    private Time time;
    public TestViewModel(){
        time = new Time();
        // 修改liveData包裝的數據，主線程用setValue，其他線程PostValue
        time.getSeconds().setValue(0);
    }
    public Time getLiveData(){
        return time;
    }
}

private TestViewModel vm;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    vm = new TestViewModel();
    vm.getLiveData().getSeconds().observe(this, new Observer<Integer>() {
        @Override
        public void onChanged(Integer integer) {
            EditText ed = findViewById(R.id.ed);
            ed.setText(""+integer);
        }
    });

ActivityMainBinding binding = ActivityMainBinding.inflate(getLayoutInflater());
View view = binding.getRoot();
setContentView(view);

 @Override
    public View onCreateView (LayoutInflater inflater,
                              ViewGroup container,
                              Bundle savedInstanceState) {
        ActivityMainBinding binding = ResultProfileBinding.inflate(inflater, container, false);
        View view = binding.getRoot();
        return view;
    }

@Override
    public void onDestroyView() {
        super.onDestroyView();
        binding = null;
    }