Android：数据库是空的？

Question

我正在尝试在我的Android应用程序中使用Django数据库，我使用了这个示例：github project 这是我的文件（我真的很抱歉大量的代码）：

DatabaseManager.java

package antoni4040.barufakis;
import android.content.Context;

import com.j256.ormlite.android.apptools.OpenHelperManager;
import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;

public class DatabaseManager<H extends OrmLiteSqliteOpenHelper> {

    private H helper;

    @SuppressWarnings("unchecked")
    public H getHelper(Context context)
    {
        if(helper == null)
        {
            helper = (H) OpenHelperManager.getHelper(context, DatabaseHelper.class);
        }
        return helper;
    }

    public void releaseHelper(H helper)
    {
        if (helper != null) {
            OpenHelperManager.releaseHelper();
            helper = null;
        }
    }

}

DatabaseInitializer.java：

package antoni4040.barufakis;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class DatabaseInitializer extends SQLiteOpenHelper{

    private static String DB_PATH = "/data/data/antoni4040.barufakis/databases/";
    private static String DB_NAME = "joke.sqlite3";

    private SQLiteDatabase database;
    private final Context context;


    public DatabaseInitializer(Context context) {
        super(context, DB_NAME, null, 1);
        this.context = context;
    }

    public void createDatabase() throws IOException{

        boolean dbExist = checkDatabase();

        if(!dbExist){
            this.getReadableDatabase();
            try {
                copyDatabase();
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
        }

    }
    private boolean checkDatabase(){

        SQLiteDatabase checkDB = null;

        try{
            String myPath = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

        }catch(SQLiteException e){
        }

        if(checkDB != null){
            checkDB.close();
        }

        return checkDB != null ? true : false;
    }
    private void copyDatabase() throws IOException{

        InputStream myInput = context.getAssets().open(DB_NAME);

        String outFileName = DB_PATH + DB_NAME;

        OutputStream myOutput = new FileOutputStream(outFileName);

        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer))>0){
            myOutput.write(buffer, 0, length);
        }

        myOutput.flush();
        myOutput.close();
        myInput.close();

    }

    @Override
    public synchronized void close() {
        if(database != null)
            database.close();

        super.close();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }

}

DatabaseHelper.java：

package antoni4040.barufakis;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;

import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
import com.j256.ormlite.dao.Dao;
import com.j256.ormlite.dao.DaoManager;
import com.j256.ormlite.support.ConnectionSource;
import com.j256.ormlite.table.TableUtils;

import java.io.IOException;
import java.sql.SQLException;

public class DatabaseHelper extends OrmLiteSqliteOpenHelper {

    private static final String DATABASE_NAME = "joke.sqlite3";
    private static final int DATABASE_VERSION = 1;

    private Dao<Joke, String> jokeDao = null;


    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);

       DatabaseInitializer initializer = new DatabaseInitializer(context);
        try {
            initializer.createDatabase();
            initializer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


    @Override
    public void onCreate(SQLiteDatabase db, ConnectionSource connectionSource) {
        try {
            Log.i(DatabaseHelper.class.getName(), "onCreate");

            TableUtils.createTable(connectionSource, Joke.class);

        } catch (SQLException e) {
            Log.e(DatabaseHelper.class.getName(), "Can't create database", e);
            throw new RuntimeException(e);
        }
    }


    @Override
    public void onUpgrade(SQLiteDatabase db, ConnectionSource connectionSource, int oldVersion, int newVersion) {
        try {
            Log.i(DatabaseHelper.class.getName(), "onUpgrade");

            TableUtils.dropTable(connectionSource, Joke.class, true);

            onCreate(db);
        } catch (SQLException e) {
            Log.e(DatabaseHelper.class.getName(), "Can't drop databases", e);
            throw new RuntimeException(e);
        }
    }


    public Dao<Joke, String> getJokeDao() throws SQLException {
        if (jokeDao == null) {
            jokeDao = DaoManager.createDao(getConnectionSource(), Joke.class);
        }
        return jokeDao;
    }



    @Override
    public void close() {
        super.close();
        jokeDao = null;
    }
}

Repo.java：

package antoni4040.barufakis;
import android.content.Context;

public class Repo {

    DatabaseHelper db;

    public RepoJoke Joke;

    public Repo(Context context)
    {
        DatabaseManager<DatabaseHelper> manager = new DatabaseManager<DatabaseHelper>();
        db = manager.getHelper(context);

        Joke = new RepoJoke(db);

    }

}

RepoJoke.java：

package antoni4040.barufakis;


import com.j256.ormlite.dao.Dao;

import java.sql.SQLException;
import java.util.List;

public class RepoJoke {

    Dao<Joke, String> jokeDao;

    public RepoJoke(DatabaseHelper db)
    {
        try {
            jokeDao = db.getJokeDao();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public int create(Joke joke)
    {
        try {
            return jokeDao.create(joke);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return 0;
    }
    public int update(Joke joke)
    {
        try {
            return jokeDao.update(joke);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return 0;
    }
    public int delete(Joke joke)
    {
        try {
            return jokeDao.delete(joke);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return 0;
    }
    public List<Joke> getAll()
    {
        try {
            return jokeDao.queryForAll();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

}

所有这一切都在这里结束：

Joke_textFragment.java：

package antoni4040.barufakis;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.List;


public class Joke_textFragment extends Fragment {

    Repo repo;

    public Joke_textFragment() {
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_joke_text, container, false);
        TextView title = (TextView) rootView.findViewById(R.id.joke_title);
        TextView text = (TextView) rootView.findViewById(R.id.text);
        repo = new Repo(rootView.getContext());
        List<Joke> jokes = repo.Joke.getAll();
        for(Joke element : jokes){
            Log.v("Element:", String.valueOf(element.getEnd()));
        }
        title.setText(jokes.get(6).getText());
        return rootView;
    }
}

最后，我无法访问第6个元素，因为数组似乎的大小为0，而我的Django数据库中有160行。