Android 带有 ArrayAdapter 的 LiveData 列表视图

Question

您好，我试图将实时数据添加到主 activity 中的列表视图数据适配器，但卡住了，谁能告诉我为什么这不起作用？

RecordViewModel：

public class RecordViewModel extends AndroidViewModel  {

    private Repository mRepository;

    public static LiveData<List<Record>> mAllRecords;

    public RecordViewModel (Application application) {
        super(application);
        mRepository = new Repository(application);
        mAllRecords = mRepository.getAllRecords();
    }

    public LiveData<List<Record>> getAllWords() {
        mAllRecords=mRepository.getAllRecords();
        return mAllRecords; }

主要Activity:

public class MainActivity extends AppCompatActivity implements SensorEventListener {
viewModel = new RecordViewModel(getApplication());
//should I use viewModel.getAllWords() to fetch data from database into mAllRecords?
@Override
protected void onCreate(Bundle savedInstanceState) {
lv = findViewById(R.id.listview);
ArrayAdapter adapter = new ArrayAdapter(this,
android.R.layout.simple_list_item_1, android.R.id.text1, mAllRecords);
//I am getting error here, can't resolve constructor
 lv.setAdapter(adapter);

我不清楚实时数据到数组适配器的转换。

Answer 1

你只需要像这样观察来自记录的实时数据

public class MainActivity extends AppCompatActivity implements SensorEventListener {
viewModel = new RecordViewModel(getApplication());
//should I use viewModel.getAllWords() to fetch data from database into mAllRecords? yes you should do it on OnCreate
@Override
protected void onCreate(Bundle savedInstanceState) {
lv = findViewById(R.id.listview);
viewModel.getAllWords();
final Observer<List<Record>> wordObserve = new Observer<List<Record>>() {
            @Override
            public void onChanged(@Nullable final allRecords List<Record>) {
                // Update the UI, in this case, a TextView.
                ArrayAdapter adapter = new ArrayAdapter(this,
                         android.R.layout.simple_list_item_1, android.R.id.text1, allRecords);
                lv.setAdapter(adapter);
            }
        };

viewModel.mAllRecords().observe(this, wordObserve);

如果我错了请纠正我，因为如果在这里使用 Kotlin 会很容易 reference

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