在设备上运行时没有这样的表错误，但在模拟器上相同的代码工作正常

Question

I have a very weird problem I am writing a code that gets data from database to show it in listView, so I've made a class for getting the database and other one for the adapter. But when I run it on device I got no such table error, although it's working fine on emulator. Also, I tried this code with another database in the same project and it's working. I added the android_metadata table to them, but still not working.

This is my db class

public class Directory_DB extends SQLiteOpenHelper{

private static String TAG = "DataBaseHelper"; // Tag just for the LogCat window
//destination path (location) of our database on device
private static String DB_PATH = ""; 
private static String DB_NAME ;// Database name
private SQLiteDatabase mDataBase; 
private final Context mContext;
private String TABLE_NAME;

public Directory_DB(Context context , String DB_NAME ) 
{
    super(context , DB_NAME, null , 2);// 1? its Database Version
    DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
    this.mContext = context;
    this.DB_NAME = DB_NAME;

}   

public void createDataBase() throws IOException
{
    //If database not exists copy it from the assets

    boolean mDataBaseExist = checkDataBase();
    if(!mDataBaseExist)
    {
        this.getReadableDatabase();
        this.close();
        try 
        {
            //Copy the database from assests
            copyDataBase();
            Log.e(TAG, "createDatabase database created");
        } 
        catch (IOException mIOException) 
        {
            throw new Error("ErrorCopyingDataBase");
        }
    }
}
    //Check that the database exists here: /data/data/your package/databases/Da Name
    private boolean checkDataBase()
    {
        File dbFile = new File(DB_PATH + DB_NAME);
        Log.v("dbFile", dbFile + "   "+ dbFile.exists());
        return dbFile.exists();
    }

    //Copy the database from assets
    private void copyDataBase() throws IOException
    {
        InputStream mInput = mContext.getAssets().open(DB_NAME);
        String outFileName = DB_PATH + DB_NAME;
        OutputStream mOutput = new FileOutputStream(outFileName);
        byte[] mBuffer = new byte[1024];
        int mLength;
        while ((mLength = mInput.read(mBuffer))>0)
        {
            mOutput.write(mBuffer, 0, mLength);
        }
        mOutput.flush();
        mOutput.close();
        mInput.close();
    }

    //Open the database, so we can query it
    public boolean openDataBase() throws SQLException
    {
        String mPath = DB_PATH + DB_NAME;
        //Log.v("mPath", mPath);
        mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
        //mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
        return mDataBase != null;
    }

    @Override
    public synchronized void close() 
    {
        if(mDataBase != null)
            mDataBase.close();
        super.close();
    }




@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub

}

}

and this is my adapter class

public class DirectoryAdapter {
public static final String TAG_ID = "_id";
public static String TAG_TABLE_NAME;

protected static final String TAG = "DataAdapter";

private final Context mContext;
private SQLiteDatabase mDb;
private Directory_DB mDbHelper;

public DirectoryAdapter(Context context, String DB_NAME, String TABLE_NAME) {
    this.mContext = context;
    mDbHelper = new Directory_DB(mContext, DB_NAME );
    this.TAG_TABLE_NAME = TABLE_NAME;
    Log.d("Database name in adapter", DB_NAME);
    Log.d("Table name in adapter", TAG_TABLE_NAME);
}

public DirectoryAdapter createDatabase() throws SQLException {
    try {
        mDbHelper.createDataBase();
    } catch (IOException mIOException) {
        Log.e(TAG, mIOException.toString() + "  UnableToCreateDatabase");
        throw new Error("UnableToCreateDatabase");
    }
    return this;
}

public DirectoryAdapter open() throws SQLException {
    try {
        mDbHelper.openDataBase();
        mDbHelper.close();
        mDb = mDbHelper.getReadableDatabase();
    } catch (SQLException mSQLException) {
        Log.e(TAG, "open >>" + mSQLException.toString());
        throw mSQLException;
    }
    return this;
}

public void close() {
    mDbHelper.close();
}

public Cursor getTestData() {
    try {

        String sql = "SELECT * FROM " + TAG_TABLE_NAME;
        Cursor mCur = mDb.rawQuery(sql, null);

        return mCur;
    } catch (SQLException mSQLException) {
        Log.e(TAG, "getTestData >>" + mSQLException.toString());
        throw mSQLException;
    }
}

}

Answer 1

您可以从设备中卸载应用程序并再次运行它。如果您稍后在数据库中添加了表，则不会反映它，因为您的数据库已经创建，并且仅在创建数据库时才创建表。

Answer 2

You have to call your createDataBase method inside the on create method

 @Override
 public void onCreate(SQLiteDatabase db) {
     // TODO Auto-generated method stub
 }

that's what's this method is for. Also if you're calling it form any where else (I didn't read your whole code) don't.