我正在创建一个名为motodescriptive的应用程序，并使用room数据库来存储我的数据（摩托车的名称、描述和URL）。在我的模拟器上一切都运行得很好，但是昨天我试着在手机上运行这个应用程序，而recyclerview完全是空白的，可能是因为一个空的数据库。你可以在下面查我的代码，提前谢谢。
这是我的appdatabase.java文件

package com.example.motodescriptive;

import android.content.Context;

import androidx.annotation.NonNull;
import androidx.room.Database;
import androidx.room.Room;
import androidx.room.RoomDatabase;
import androidx.room.migration.Migration;
import androidx.sqlite.db.SupportSQLiteDatabase;

@Database(entities = {MotoEntity.class}, version = 14)
public abstract class AppDatabase extends RoomDatabase {
    private static AppDatabase instance;
    private static String NAME = "moto-database";
    public abstract MotoDao motoDao();

    public static synchronized AppDatabase getInstance(Context context) {
        if(instance == null) {
            instance = Room.databaseBuilder(context, AppDatabase.class, NAME).fallbackToDestructiveMigration().allowMainThreadQueries().addMigrations(MIGRATION_13_14).build();

        }
        return instance;

    }

    static final Migration MIGRATION_13_14 = new Migration(13, 14) {
        @Override
        public void migrate(@NonNull SupportSQLiteDatabase database) {

        }
    };

}

motodao.java文件

package com.example.motodescriptive;

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

import java.util.List;

@Dao
public interface MotoDao {
    @Query("SELECT * FROM motoentity")
    List<MotoEntity> selectAll();

    @Query("SELECT * FROM motoentity WHERE moto_name LIKE :name")
    List<MotoEntity> checkForName(String name);

    @Query("SELECT COUNT(*) FROM motoentity where moto_name = :name")
    int agentsCount(String name);

    @Insert
    void insert(MotoEntity motoEntity);

    @Update
    void update(MotoEntity motoEntity);

    @Delete
    void delete(MotoEntity motoEntity);

    @Query("DELETE FROM motoentity where ID = :motoid")
    void deleteById(int motoid);

}

motonentity.java文件

package com.example.motodescriptive;

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

import java.io.Serializable;

@Entity
public class MotoEntity implements Serializable {
    @PrimaryKey(autoGenerate = true)
    public int ID;

    @ColumnInfo(name = "moto_name")
    public String moto_name;

    @ColumnInfo(name = "moto_desc")
    public String moto_desc;

    @ColumnInfo(name = "moto_longdesc")
    public String moto_longdesc;

    @ColumnInfo(name = "moto_longdesc2")
    public String moto_longdesc2;

    @ColumnInfo(name = "moto_longdesc3")
    public String moto_longdesc3;

    @ColumnInfo(name = "moto_longdesc4")
    public String moto_longdesc4;

    public String getMoto_longdesc2() {
        return moto_longdesc2;
    }

    public void setMoto_longdesc2(String moto_longdesc2) {
        this.moto_longdesc2 = moto_longdesc2;
    }

    public String getMoto_longdesc3() {
        return moto_longdesc3;
    }

    public void setMoto_longdesc3(String moto_longdesc3) {
        this.moto_longdesc3 = moto_longdesc3;
    }

    public String getMoto_longdesc4() {
        return moto_longdesc4;
    }

    public void setMoto_longdesc4(String moto_longdesc4) {
        this.moto_longdesc4 = moto_longdesc4;
    }

    public String getMoto_longdesc() {
        return moto_longdesc;
    }

    public void setMoto_longdesc(String moto_longdesc) {
        this.moto_longdesc = moto_longdesc;
    }

    @ColumnInfo(name = "moto_img")
    public String moto_img;

    public int getID() {
        return ID;
    }

    public void setID(int ID) {
        this.ID = ID;
    }

    public String getMoto_name() {
        return moto_name;
    }

    public void setMoto_name(String moto_name) {
        this.moto_name = moto_name;
    }

    public String getMoto_desc() {
        return moto_desc;
    }

    public void setMoto_desc(String moto_desc) {
        this.moto_desc = moto_desc;
    }

    public String getMoto_img() {
        return moto_img;
    }

    public void setMoto_img(String moto_img) {
        this.moto_img = moto_img;
    }
}

最后，在这里，我将数据库中的数据添加到一个arraylist中，并将其传递给适配器。我把我的数据放到了数据库里。因为这部分代码已经存储在数据库中，所以我不再需要它了，所以我删除了它。

List<MotoEntity> motorcycles = appDatabase.motoDao().selectAll();

        adapter = new MotorAdapter((ArrayList<MotoEntity>) motorcycles, this, getApplicationContext());
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));