java - 我应该传递什么上下文 WorkManager.getInstance().enqueue() ?(使用 MVVM + 房间数据库 + WorkManager)
问题描述
我正在尝试通过存储库方法将 WorkManager 工作人员排队,以便在我的数据库中插入一些数据,但我似乎无法弄清楚我应该在 getInstance() 中传递什么类型的上下文。显然,我给出的上下文是错误的,因为我得到了 NullPointerException。我是 Android 开发的新手,上下文的概念可能会令人困惑。我已经尝试了一切,但我相信这很简单。我正在使用 MVVM(如果我不应该将 Worker 加入存储库中,请告诉我)+ RoomDatabase。
AddWorkoutRepository.java
public class AddWorkoutRepository {
private static final String REPOSITORY_TAG = "REPOSITORY TAG";
private AddWorkoutWorker worker;
private WorkoutDAO workoutDAO;
//private LiveData<List<Workout>> workouts;
public AddWorkoutRepository(Application application){
AppDatabase database = AppDatabase.getInstance(application);
workoutDAO = database.workoutDAO();
//workouts = workoutDAO.getAllWorkoutsLiveData();
}
/*public LiveData<List<Workout>> getAllWorkouts(){
return workouts;
}*/
public void insertWorkout(Workout workout){
String workoutName = workout.getWorkoutName();
String workoutType = workout.getWorkoutType();
Log.d(REPOSITORY_TAG, "Insert Values passed: "+workoutName + workoutType);
Data data = new Data.Builder()
.putString(WORK_WORKOUT_NAME, workoutName)
.putString(WORK_WORKOUT_TYPE, workoutType)
.build();
OneTimeWorkRequest importDataRequest = new OneTimeWorkRequest.Builder(AddWorkoutWorker.class)
.setInputData(data)
.addTag("Importing Single Workout" + workoutName + " and " + workoutType)
.build();
WorkManager.getInstance(worker.getApplicationContext()).enqueue(importDataRequest);
Log.d(REPOSITORY_TAG, "After work manager task OK");
}
}
AddWorkoutWorker.java
public class AddWorkoutWorker extends Worker {
public static final String WORK_WORKOUT_NAME = "workout";
public static final String WORK_WORKOUT_TYPE = "type";
private static final String WORKER_TAG = "Worker Tag";
private WorkoutDAO workoutDAO;
public AddWorkoutWorker(@NonNull Context context, @NonNull WorkerParameters workerParams) {
super(context, workerParams);
}
@NonNull
@Override
public Result doWork() {
Data inputData = getInputData();
String workoutName = inputData.getString(WORK_WORKOUT_NAME);
String workoutType = inputData.getString(WORK_WORKOUT_TYPE);
if (workoutName != null && workoutType != null){
Log.d(WORKER_TAG,"Worker data passed: "+workoutName + workoutType);
Workout workout = new Workout(workoutName, workoutType);
workoutDAO.insertSingleWorkout(workout);
}else{
return Result.failure();
}
return Result.success();
}
}
如果需要更多代码,请随时问我。非常感谢您提前提供的帮助!
解决方案
你有 NullPointerExceptionWorkManager.getInstance(worker.getApplicationContext()).enqueue(importDataRequest);
因为工作 字段没有初始化,它的默认值为空。您不应该在每个 insertWorkout(Workout锻炼) 方法调用中获取 WorkManager 的实例。而不是这个传递 WorkManager 实例作为 AddWorkoutRepository 的构造函数中的依赖项。对于上下文,您可以改用活动上下文或应用程序上下文。如果您不喜欢这种方法,您可以在 AddWorkoutRepository 类中添加 WorkManager 字段并在 AddWorkoutRepository 构造函数中对其进行初始化,并使用 Application 对象作为上下文。
更新您的 AddWorkoutRepository 类:
public class AddWorkoutRepository {
private static final String REPOSITORY_TAG = "REPOSITORY TAG";
private static final String WORK_WORKOUT_NAME = "work_name";
private static final String WORK_WORKOUT_TYPE = "work_time";
private final WorkManager workManager;
private AddWorkoutWorker worker;
private WorkoutDAO workoutDAO;
//private LiveData<List<Workout>> workouts;
public AddWorkoutRepository(Application application){
AppDatabase database = AppDatabase.getInstance(application);
workoutDAO = database.workoutDAO();
workManager = WorkManager.getInstance(application.getApplicationContext());
//workouts = workoutDAO.getAllWorkoutsLiveData();
}
/*public LiveData<List<Workout>> getAllWorkouts(){
return workouts;
}*/
public void insertWorkout(Workout workout){
String workoutName = workout.getWorkoutName();
String workoutType = workout.getWorkoutType();
Log.d(REPOSITORY_TAG, "Insert Values passed: "+workoutName + workoutType);
Data data = new Data.Builder()
.putString(WORK_WORKOUT_NAME, workoutName)
.putString(WORK_WORKOUT_TYPE, workoutType)
.build();
OneTimeWorkRequest importDataRequest = new OneTimeWorkRequest.Builder(AddWorkoutWorker.class)
.setInputData(data)
.addTag("Importing Single Workout" + workoutName + " and " + workoutType)
.build();
workManager.enqueue(importDataRequest);
Log.d(REPOSITORY_TAG, "After work manager task OK");
}
}
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