MVVM Android 視圖未更新

Question

我是 Android MVVM 的新手，帶有 livedata，創建的文件夾結構為 model，視圖模型和視圖視圖頁面未更新，添加了 gradle

def lifecycle_version = "2.3.1" 
implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-livedata:$lifecycle_version"

變化正在發生，我可以在日志中看到，但變化並沒有反映在視圖中。 我的 model class

public class SplashScreenModel {
    private String message;
    private Boolean inProgress;    
    public String getMessage() {
        return message;
    }    
    public void setMessage(String message) {
        this.message = message;
    }    
    public Boolean getInProgress() {
        return inProgress;
    }    
    public void setInProgress(Boolean inProgress) {
        this.inProgress = inProgress;
    }
}

視圖模型

public class SplashScreenViewModel extends BaseViewModel {

    //#region VARIABLES
    public static final String TAG="SPLASH VM";
    private ConfigRepository configRepository;
    private MyAsyncTask myAsyncTask;

    private MutableLiveData<String> message = new MutableLiveData<>();
    public MutableLiveData<String> getMessage() {
        return message;
    }
    public void setMessage(String message){
        this.message.setValue(message);
    }

    public void showMessage(String s){
        message.setValue(s);
    }

    //#endregion
    public SplashScreenViewModel(@NonNull Application application) {
        super(application);
        configRepository = new ConfigRepository(application);
        myAsyncTask = new MyAsyncTask();
    }

    public void test(){
        myAsyncTask.execute();
    }


    private class MyAsyncTask extends AsyncTask<Void,Integer,Void> {
        @Override
        protected Void doInBackground(Void... voids) {
            try {
                for (int n=1; n<=10; n++){
                    Log.d(TAG, "background: Loop "+n);
                    Thread.sleep(500);
                    publishProgress(n);
                }

            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            super.onProgressUpdate(values);
            showMessage(String.valueOf(values[0]));
        }

        @Override
        protected void onPostExecute(Void unused) {
            super.onPostExecute(unused);
            Log.d(TAG, "onPostExecute: Executed");
            showMessage("Done");
        }
    }
}

活動

public class SplashActivity extends AppCompatActivity {

    //#region VARIABLE
    private static final String TAG="SPLASH";
    private SplashScreenViewModel splashViewModel;
    private String text ="Begins";
    //TextView textView;
    ActivitySplashBinding binding;


    //#endregion

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_splash);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_splash);

        //textView = findViewById(R.id.lbl_splash_message);

        splashViewModel = new ViewModelProvider(this).get(SplashScreenViewModel.class);
        splashViewModel.showMessage("abhi waiting...");
        //binding.lblSplashMessage.setText(text);

        splashViewModel.getMessage().observe(this, s -> {
            //Toast.makeText(SplashActivity.this,s,Toast.LENGTH_SHORT).show();
            Log.d(TAG, "onChanged: "+s);
            String d = splashViewModel.getMessage().getValue();
            Log.d(TAG, "message value: "+d);
            binding.lblSplashMessage.setText(d); // by doing like am getting desired result.
            // but how it automatically reflect on view.
        });
        splashViewModel.test();
    }
}

閃屏布局

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable
            name="splashViewModel"
            type="com.fonz.pos_quick_pay.ui.main.viewmodel.SplashScreenViewModel" />
    </data>
    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:theme="@style/SplashTheme"
        tools:context=".ui.main.view.SplashActivity">
        <ProgressBar
            android:id="@+id/progress_splash"
            style="?android:attr/progressBarStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="20dp"
            app:layout_constraintBottom_toTopOf="@id/lbl_splash_message"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent" />    
        <TextView
            android:id="@+id/lbl_splash_message"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="120dp"
            android:text="@{splashViewModel.message}"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent" />    
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

基本視圖 Model

public abstract class BaseViewModel extends AndroidViewModel {
    private final ObservableBoolean mIsLoading = new ObservableBoolean();    
    public BaseViewModel(@NonNull Application application) {
        super(application);
    }    
    public ObservableBoolean getIsLoading() {
        return mIsLoading;
    }    
    public void setIsLoading(boolean isLoading) {
        mIsLoading.set(isLoading);
    }
}

請幫我解決。

Answer 1

將此添加到您的創建活動中

   binding.lifecycleOwner= this