我正在尝试使用预填充的 Room 数据库，但在尝试使用该数据库时出现崩溃，并出现以下错误：
java.lang.NullPointerException: cursor.getString(toColumnIndex) must not be null一切正常，直到我添加
createFromAsset("databses/test.db")getAllCocktails()我尝试使用 Room 的版本 2.5.1 和 2.5.2
活动：
public class PedirTragoActivity extends AppCompatActivity {
AppDatabase db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pedir_trago1_1);
db = AppDatabase.getInstance(this.getApplication());
db.cocktailDAO().getAllCocktails();
}
}
房间数据库：
@Database(entities = {
/**Entities*/
},
version = 7)
public abstract class AppDatabase extends RoomDatabase {
public static AppDatabase INSTANCE;
public abstract CocktailDAO cocktailDAO();
/**More things*/
public static AppDatabase getInstance(Context context) {
if (INSTANCE == null) {
INSTANCE = Room.databaseBuilder(context, AppDatabase.class, "barbotApp.db")
.allowMainThreadQueries()
.fallbackToDestructiveMigration()
.createFromAsset("databases/test.db")
.build();
}
return INSTANCE;
}
}
日志猫：
2023-09-23 17:17:20.600 8250-8250 Choreographer com.mecatronica.barbot I Skipped 67 frames! The application may be doing too much work on its main thread.
2023-09-23 17:17:20.801 8250-8594 AdrenoGLES-0 com.mecatronica.barbot I QUALCOMM build : 03e27f8, I326e6aff90
Build Date : 11/02/20
OpenGL ES Shader Compiler Version: EV031.32.02.04
Local Branch : mybrancheb1d781c-1a78-f1f4-8c78-ac1f6bcc2cee
Remote Branch : quic/gfx-adreno.lnx.1.0.r116-rel
Remote Branch : NONE
Reconstruct Branch : NOTHING
2023-09-23 17:17:20.801 8250-8594 AdrenoGLES-0 com.mecatronica.barbot I Build Config : S P 10.0.7 AArch64
2023-09-23 17:17:20.801 8250-8594 AdrenoGLES-0 com.mecatronica.barbot I Driver Path : /vendor/lib64/egl/libGLESv2_adreno.so
2023-09-23 17:17:20.813 8250-8594 AdrenoGLES-0 com.mecatronica.barbot I PFP: 0x016ee190, ME: 0x00000000
2023-09-23 17:17:21.019 8250-8594 LB com.mecatronica.barbot E fail to open file: No such file or directory
2023-09-23 17:17:21.021 8250-8594 OpenGLRenderer com.mecatronica.barbot I Davey! duration=1547ms; Flags=1, IntendedVsync=42335033169415, Vsync=42336149836037, OldestInputEvent=9223372036854775807, NewestInputEvent=0, HandleInputStart=42336161943432, AnimationStart=42336162004370, PerformTraversalsStart=42336162065047, DrawStart=42336409293120, SyncQueued=42336445054213, SyncStart=42336445465515, IssueDrawCommandsStart=42336445624838, SwapBuffers=42336577074578, FrameCompleted=42336581385203, DequeueBufferDuration=272760, QueueBufferDuration=682187, GpuCompleted=1893829464,
2023-09-23 17:17:21.027 8250-8250 Looper com.mecatronica.barbot W PerfMonitor doFrame : time=424ms vsyncFrame=0 latency=1127ms procState=2 historyMsgCount=10 (msgIndex=1 wall=1223ms seq=4 running=1128ms runnable=12ms late=2999ms h=android.app.ActivityThread$H w=159) (msgIndex=5 wall=1007ms seq=8 running=2ms runnable=1ms io=4ms late=3591ms h=android.app.ActivityThread$H w=127)
2023-09-23 17:17:21.154 8250-8250 Looper com.mecatronica.barbot W PerfMonitor doFrame : time=35ms vsyncFrame=0 latency=459ms procState=2 historyMsgCount=4 (msgIndex=1 wall=424ms seq=14 running=255ms runnable=1ms late=1127ms h=android.view.Choreographer$FrameHandler c=android.view.Choreographer$FrameDisplayEventReceiver) (msgIndex=4 wall=78ms seq=17 running=70ms runnable=2ms late=413ms h=android.view.ViewRootImpl$ViewRootHandler c=androidx.appcompat.app.AppCompatDelegateImpl$2)
2023-09-23 17:17:28.708 8250-8250 MiuiFrameworkFactory com.mecatronica.barbot V get AllImpl object = android.common.MiuiFrameworkFactoryImpl@b038154
2023-09-23 17:17:28.726 8250-8250 MirrorManager com.mecatronica.barbot W this model don't Support
2023-09-23 17:17:28.773 8250-8250 Timeline com.mecatronica.barbot I Timeline: Activity_launch_request time:42344334
2023-09-23 17:17:28.996 8250-8250 DecorView[] com.mecatronica.barbot D getWindowModeFromSystem windowmode is 1
2023-09-23 17:17:28.997 8250-8250 DecorView com.mecatronica.barbot D createDecorCaptionView windowingMode:1 mWindowMode 1 isFullscreen: true
2023-09-23 17:17:30.631 8250-8250 AndroidRuntime com.mecatronica.barbot D Shutting down VM
2023-09-23 17:17:30.646 8250-8250 AndroidRuntime com.mecatronica.barbot E FATAL EXCEPTION: main
Process: com.mecatronica.barbot, PID: 8250
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mecatronica.barbot/com.mecatronica.barbot.PedirTragoActivity}: java.lang.NullPointerException: cursor.getString(toColumnIndex) must not be null
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3550)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3710)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2146)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8057)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
Caused by: java.lang.NullPointerException: cursor.getString(toColumnIndex) must not be null
at androidx.room.util.TableInfoKt.readForeignKeyFieldMappings(TableInfo.kt:536)
at androidx.room.util.TableInfoKt.readForeignKeys(TableInfo.kt:488)
at androidx.room.util.TableInfoKt.readTableInfo(TableInfo.kt:472)
at androidx.room.util.TableInfo$Companion.read(TableInfo.kt:130)
at androidx.room.util.TableInfo.read(Unknown Source:2)
at com.mecatronica.barbot.database.AppDatabase_Impl$1.onValidateSchema(AppDatabase_Impl.java:136)
at androidx.room.RoomOpenHelper.onCreate(RoomOpenHelper.kt:72)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.onCreate(FrameworkSQLiteOpenHelper.kt:244)
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:411)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:316)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.getWritableOrReadableDatabase(FrameworkSQLiteOpenHelper.kt:232)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.innerGetDatabase(FrameworkSQLiteOpenHelper.kt:190)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.getSupportDatabase(FrameworkSQLiteOpenHelper.kt:151)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper.getWritableDatabase(FrameworkSQLiteOpenHelper.kt:104)
at androidx.room.SQLiteCopyOpenHelper.getWritableDatabase(SQLiteCopyOpenHelper.kt:71)
at androidx.room.RoomDatabase.inTransaction(RoomDatabase.kt:638)
at androidx.room.RoomDatabase.assertNotSuspendingTransaction(RoomDatabase.kt:457)
at com.mecatronica.barbot.database.daos.CocktailDAO_Impl.getAllCocktails(CocktailDAO_Impl.java:177)
at com.mecatronica.barbot.PedirTragoActivity.onCreate(PedirTragoActivity.java:63)
at android.app.Activity.performCreate(Activity.java:8157)
at android.app.Activity.performCreate(Activity.java:8129)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1310)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3523)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3710)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2146)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8057)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
2023-09-23 17:17:30.716 8250-8250 Process com.mecatronica.barbot I Sending signal. PID: 8250 SIG: 9
一切正常，直到我添加 createFromAsset("databses/test.db") 方法
然后从 logcat 中：-
cursor.getString(toColumnIndex) 不能为 null
可能是由于当
@Entity在您实际尝试检索数据之前，这似乎不会成为问题，因此只有当您从资产引入数据时才会出现问题。
您有两个选择：-
@Entity您可能希望修改您的问题以包括：-
@Entity@Dao