我正在尝试使用Room的createFromAsset方法从资产文件夹中复制预填充的SQLite数据库。数据库相当大（一个表有~370k个条目；大约18mb的总大小）。数据库在数据库文件夹中创建，它包含适用的表，但没有数据传输到表中。

我已经复习了以下SO问题，但还没有找到解决方案：

1. 如何从资产预填充房间数据库？
2. 房间：未创建数据库
3. 如何从资产重新创建房间数据库？
4. Android Room Library无法从Asset复制数据库
5. 房间：未创建数据库

我还查看了以下信息页面：

1. 预填充您的Room数据库
2. 房间数据库。生成器
3. 打包房间：使用这一方法预填充数据库
4. Android Room with a View-Java-Codelab

我尝试等待几分钟，看看数据库填充是否需要时间，但没有数据出现。我一直在使用AS的设备文件资源管理器从虚拟设备下载数据库，并在SQLiteDB浏览器中打开它，以及使用AS的数据库检查器。

此外，LogCat始终显示以下内容（每次在MainActivity中记录）：

D/MainActivity： onCreate前10个未找到的好词

表1-"bad_words"
列1-"word"， TEXT
表2-"english_words"
列1-"id"，INTEGER
列2-"word"，TEXT
列3-"频率"，INTEGER

app build. gradle依赖项：

dependencies {

    implementation fileTree(dir: 'libs', include: ['*.jar'])
    testImplementation 'junit:junit:4.13.1'
    implementation 'androidx.appcompat:appcompat:1.3.1'
    implementation 'com.google.android.material:material:1.4.0'
    // For Room database
    def room_version = "2.3.0"
    implementation "androidx.room:room-runtime:$room_version"
    annotationProcessor "androidx.room:room-compiler:$room_version"
    testImplementation "androidx.room:room-testing:$room_version"

}

ValidWords实体：

import androidx.annotation.NonNull;
import androidx.room.ColumnInfo;
import androidx.room.Entity;
import androidx.room.PrimaryKey;

@Entity(tableName = "english_words")
public class ValidWords {
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "id")
    public int mID;

    @ColumnInfo(name = "word")
    @NonNull
    public String mWord;

    @ColumnInfo(name = "frequency")
    public int mFrequency;

    public ValidWords(@NonNull String word) {this.mWord = word;}

    public String getWord() {return this.mWord;}

    public void setWord(@NonNull String word) {this.mWord = word;}

    public int getFrequency() {return mFrequency;}

    public void setFrequency(int frequency) {this.mFrequency = frequency;}
}

BadWords实体：

import androidx.annotation.NonNull;
import androidx.room.ColumnInfo;
import androidx.room.Entity;
import androidx.room.PrimaryKey;

@Entity (tableName = "bad_words")
public class BadWords {
    @PrimaryKey
    @NonNull
    @ColumnInfo(name = "word")
    public String mWord;

    public BadWords(@NonNull String word) {this.mWord = word;}

    @NonNull
    public String getWord() {return mWord;}

    public void setWord(@NonNull String mWord) {this.mWord = mWord;}
}

wordDAO接口：

import androidx.room.Dao;
import androidx.room.Insert;
import androidx.room.Query;

import java.util.List;

@Dao
public interface wordsDAO {
    @Query("SELECT * FROM english_words LIMIT 10")
    List<ValidWords> getFirstTenGoodWords();

    @Query("SELECT * FROM bad_words")
    List<BadWords> getBadWords();

    @Query("SELECT * FROM english_words WHERE word LIKE :wordToCheck LIMIT 1")
    ValidWords getMatch(String wordToCheck);

    @Insert(entity = ValidWords.class)
    long insertGoodWordInfo(ValidWords validWord);
}

参考WordsDB数据库：

import android.content.Context;
import androidx.room.Database;
import androidx.room.Room;
import androidx.room.RoomDatabase;

@Database(entities = {BadWords.class, ValidWords.class}, version = 2)
public abstract class ReferenceWordsDB extends RoomDatabase {

    public abstract wordsDAO wordsDAO();

    private static volatile ReferenceWordsDB INSTANCE;

    static ReferenceWordsDB getDatabase(final Context context){
        if (INSTANCE == null){
            synchronized (ReferenceWordsDB.class){
                if (INSTANCE == null){
                    INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
                            ReferenceWordsDB.class, "GoodWordsAndFrequency.db")
                            .createFromAsset("GoodWordsAndFrequency.db")
                            .fallbackToDestructiveMigration()
                            .allowMainThreadQueries()
                            .build();
                }
            }
        }
        return INSTANCE;
    }
}

主要活动：

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.InputMethodManager;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.core.content.res.ResourcesCompat;

import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

public class MainActivity extends AppCompatActivity {

    private static ArrayList<ArrayList<ValidWords>> infoFromFindActualWordRunnableClass;
    private final String LOG_CLASS = "MainActivity";
    private ReferenceWordsDB wordsDB;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        final String METHOD = "onCreate";
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        getViews();

        wordsDB = ReferenceWordsDB.getDatabase(this);
        List<ValidWords> first10GoodWords = new ArrayList<>(wordsDB.wordsDAO().getFirstTenGoodWords());

        if (first10GoodWords.size() == 0){
            Log.d(LOG_CLASS, String.format(Locale.US, "%s 1st 10 good words NOT FOUND", METHOD));
        }
        for (ValidWords currentWord : first10GoodWords){
            Log.d(LOG_CLASS, String.format(Locale.US, "%s currentWord word = %s, frequency = %d", METHOD, currentWord.getWord(), currentWord.getFrequency()));
        }

...
    }
}

我正在使用安装了所有已知更新的Android Studio 4.2.2。