Question

我刚刚为我的应用程序完成了以下教程： https://codelabs.developers.google.com/codelabs/android-room-with-a-view/#4

但是我的问题是，即使我插入了数据，我的数据库仍然是空的。我通过在数据库浏览器中查看来检查它，并且其中没有记录。任何帮助将不胜感激。如果您需要更多信息。让我知道。

Dao对象类：

 @Insert(onConflict = OnConflictStrategy.REPLACE)
void insertRecord(LocationDetails Details);

我的实体类：

Entity(tableName = "location")

公共类LocationDetails {

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

@PrimaryKey(autoGenerate = true)
private int id;
private String jsonObjectString;
private double latitude;
private double longitude;
private String locationType;

public String getLocationType() {
    return locationType;
}

public void setLocationType(String locationType) {
    this.locationType = locationType;
}

public double getLatitude() {
    return latitude;
}

public void setLatitude(double latitude) {
    this.latitude = latitude;
}

public double getLongitude() {
    return longitude;
}

public void setLongitude(double longitude) {
    this.longitude = longitude;
}

public String getJsonObjectString() {
    return jsonObjectString;
}

public void setJsonObjectString(String jsonObjectString) {
    this.jsonObjectString = jsonObjectString;
}

public String toString() {
    return "Lat: " + latitude + ", Long: " + longitude;
}

}

这是我的数据库控制器类，我的ViewModel用于与数据库交互。

公共类DatabaseController {

private String TAG = getClass().getSimpleName();

private static DatabaseController sInstance;
private LiveData<List<LocationDetails>> mListOfLocations;
private Database mDatabase;

private DatabaseController(Context context) {
    mDatabase = Database.getDatabase(context);
}

public static DatabaseController getInstance() {
    return sInstance;
}

public static void initInstance(Context context) {
    sInstance = new DatabaseController(context);
}

public void addLocationRecord(LocationDetails locationDetails) {
    new insertAsyncTask(mDatabase).execute(locationDetails);
    Log.d(TAG, "Location Record Added Successfully");
}

private static class insertAsyncTask extends AsyncTask<LocationDetails, Void, Void> {

    private Database database;

    insertAsyncTask(Database database) {
        this.database = database;
    }

    @Override
    protected Void doInBackground(LocationDetails... databases) {
        database.mMyDao().insertRecord(databases[0]);
        return null;
    }
}

已经在每个步骤添加了断点并进行了检查。整个代码运行无任何异常或错误，但仍然没有在我的数据库中添加任何记录。

这里回答的问题是相同的，但是他的解决方案是不同的，因此不能重复。 Room Database Table is still empty after inserting data

我第一次收到这些日志：

2018-10-26 18:18:41.329 27827-27827/genesis.com.getlocation D/DatabaseController: Location Record Added Successfully
2018-10-26 18:18:41.345 27827-27876/genesis.com.getlocation D/Surface: Surface::disconnect(this=0x990a1f00,api=1)
2018-10-26 18:18:41.346 27827-27944/genesis.com.getlocation W/SQLiteConnection: Could not change the database journal as DB was busy. Proceeding...
2018-10-26 18:18:41.347 27827-27876/genesis.com.getlocation D/GraphicBuffer: unregister, handle(0xaaf92040) (w:848 h:1264 s:848 f:0x1 u:0x000b00)
2018-10-26 18:18:41.347 27827-27876/genesis.com.getlocation D/GraphicBuffer: unregister, handle(0xaaf92400) (w:848 h:1264 s:848 f:0x1 u:0x000b00)
2018-10-26 18:18:41.347 27827-27876/genesis.com.getlocation D/GraphicBuffer: unregister, handle(0xaaf924c0) (w:848 h:1264 s:848 f:0x1 u:0x000b00)
2018-10-26 18:18:41.347 27827-27876/genesis.com.getlocation D/Surface: Surface::disconnect(this=0x990a1f00,api=1)
2018-10-26 18:18:41.362 27827-27944/genesis.com.getlocation W/SQLiteConnection: Could not change the database journal as DB was busy. Proceeding...
2018-10-26 18:18:41.369 27827-27944/genesis.com.getlocation D/SQLiteDatabase: beginTransaction()
2018-10-26 18:18:41.372 27827-27944/genesis.com.getlocation D/SQLiteDatabase: endTransaction()
2018-10-26 18:18:41.374 27827-27827/genesis.com.getlocation D/WindowClient: Remove from mViews: DecorView@74e9112[], this = android.view.WindowManagerGlobal@fbcfdce
2018-10-26 18:18:41.377 27827-27827/genesis.com.getlocation V/InputMethodManager: onWindowFocus: null softInputMode=32 first=false flags=#81810100
2018-10-26 18:18:41.380 27827-27944/genesis.com.getlocation D/SQLiteDatabase: beginTransaction()
2018-10-26 18:18:41.384 27827-27944/genesis.com.getlocation D/SQLiteDatabase: endTransaction()
2018-10-26 18:18:41.394 27827-27873/genesis.com.getlocation I/BufferQueueProducer: [SurfaceTexture-0-27827-0](this:0xa8461000,id:0,api:1,p:27827,c:27827) queueBuffer: fps=0.67 dur=4486.29 max=3892.05 min=17.56
2018-10-26 18:18:41.403 27827-27945/genesis.com.getlocation D/SQLiteDatabase: beginTransaction()
2018-10-26 18:18:41.405 27827-27945/genesis.com.getlocation D/SQLiteDatabase: endTransaction()

此后，我始终会收到以下日志：（不同之处在于数据库正处于忙碌状态）

 2018-10-26 18:18:08.788 27080-27080/genesis.com.getlocation D/ConfirmDialogFragment: onDialogButtonClicked
2018-10-26 18:18:08.788 27080-27080/genesis.com.getlocation D/ConfirmDialogFragmentViewModel: RadioButton value is Desimus
2018-10-26 18:18:08.788 27080-27080/genesis.com.getlocation D/ConfirmDialogFragmentViewModel: Name of place is  Khan Plaza
2018-10-26 18:18:08.789 27080-27080/genesis.com.getlocation D/DatabaseController: Location Record Added Successfully
2018-10-26 18:18:08.791 27080-27775/genesis.com.getlocation D/SQLiteDatabase: beginTransaction()
2018-10-26 18:18:08.805 27080-27775/genesis.com.getlocation D/SQLiteDatabase: endTransaction()
2018-10-26 18:18:08.824 27080-27166/genesis.com.getlocation D/Surface: Surface::disconnect(this=0x94b83e00,api=1)
2018-10-26 18:18:08.825 27080-27166/genesis.com.getlocation D/GraphicBuffer: unregister, handle(0xa6043c40) (w:848 h:1264 s:848 f:0x1 u:0x000b00)
2018-10-26 18:18:08.826 27080-27166/genesis.com.getlocation D/GraphicBuffer: unregister, handle(0xa60425c0) (w:848 h:1264 s:848 f:0x1 u:0x000b00)
2018-10-26 18:18:08.826 27080-27166/genesis.com.getlocation D/GraphicBuffer: unregister, handle(0xa6042680) (w:848 h:1264 s:848 f:0x1 u:0x000b00)
2018-10-26 18:18:08.826 27080-27166/genesis.com.getlocation D/Surface: Surface::disconnect(this=0x94b83e00,api=1)
2018-10-26 18:18:08.829 27080-27602/genesis.com.getlocation D/SQLiteDatabase: beginTransaction()
2018-10-26 18:18:08.831 27080-27602/genesis.com.getlocation D/SQLiteDatabase: endTransaction()
2018-10-26 18:18:08.859 27080-27080/genesis.com.getlocation D/WindowClient: Remove from mViews: DecorView@3ad944e[], this = android.view.WindowManagerGlobal@40be950
2018-10-26 18:18:08.867 27080-27080/genesis.com.getlocation V/InputMethodManager: onWindowFocus: null softInputMode=32 first=false flags=#81810100
2018-10-26 18:18:08.879 27080-27235/genesis.com.getlocation I/BufferQueueProducer: [SurfaceTexture-0-27080-1](this:0xa8460000,id:1,api:1,p:27080,c:27080) queueBuffer: fps=0.44 dur=4554.45 max=4532.60 min=21.85
2018-10-26 18:18:08.893 27080-27235/genesis.com.getlocation I/BufferQueueProducer: [SurfaceTexture-0-27080-1](this:0xa8460000,id:1,api:1,p:27080,c:27080) queueBuffer: slot 0 is dropped, handle=0xaaf91800

Answer 1

很可能您没有成功插入。

确保在插入时获得主ID 确保在后台线程上执行插入操作。确保您正在后台线程上进行检索

此外，如果您在安装后对模型进行了更改，这将导致其在触摸数据库时失败，因为架构不再与模型变量匹配。

因此，请检查数据库创建代码行，并确保您具有处理架构更改（例如更改模型）的句柄。破坏性的回退很好，如果没有人使用它，则卸载并重新安装。

Answer 2

检查您的LocationDetails类是否实现了Serializable。在扩展RoomDatabase的类中，插入要通过这种方式添加的类

 @Database(entities = {
        LocationDetails.class,
     },version = 1, exportSchema = false)

，并确保每次在数据库中添加/删除类时都更新版本号。我还建议使用room的1.1.1-rc1版本，通过在gradle中添加此行，该版本比1.1.1更加稳定

 implementation 'android.arch.persistence.room:runtime:1.1.1-rc1'

我还建议在Android 6+上（可能真的记不起7个）在线程中调用您的请求（设备的evarey AsyncTask共享同一个线程，然后等待执行DoInBackground函数，并且可以）有时最多需要5到10秒才能启动任务。

插入新数据后，会议室数据库表仍为空

2 个答案: