android数据库没有在平板电脑上阅读

基本上我正在做的是一个测验应用程序，它从数据库中读取问题以及该问题的相应选项。该应用程序适用于平板电脑，因此屏幕会显示左侧的问题列表（根据数据库中的问题数量创建），右侧显示带有四个选项的问题。我遇到的问题是，尽管它在模拟器上完美工作，但它不适用于平板电脑。我将bin文件夹中的.apk文件安装到平板电脑上，看起来没有成功读取数据库。我很抱歉，如果我即将发布的代码看起来很sl，，这是我第一次使用Android，而且我所做的一切都基于我在通过互联网阅读的各种教程中阅读的内容。android数据库没有在平板电脑上阅读

这是数据库助手：

//Declaration of the Questions Database 
public class DBHelper extends SQLiteOpenHelper{ 
//Columns to be created in the table questions 
public static final String TABLE_QUESTIONS = "questions"; 
public static final String COLUMN_QUESTIONID = "_questionid"; 
public static final String COLUMN_QUESTION = "question"; 
public static final String COLUMN_EXPLANATION = "explanation"; 
public static final String COLUMN_QIMAGE = "questionimage"; 
public static final String COLUMN_EIMAGE = "explanationimage"; 
public static final String COLUMN_MODULEID = "moduleid"; 
//***************************************************************// 
//Columns to be created in the table options 
public static final String TABLE_OPTIONS = "options"; 
public static final String COLUMN_OPTIONID = "_optionid"; 
public static final String COLUMN_OPTION = "option"; 
public static final String COLUMN_CORRECTANSWER = "correctanswer"; 
//public static final String COLUMN_QUESTIONID = "questionid"; 
//***************************************************************// 
//Database name and version 
private static final String DATABASE_NAME = "discipulus.db"; 
private static final int DATABASE_VERSION = 1; 

// Database creation SQL statement of questions table 
private static final String QUESTIONS_CREATE = "CREATE TABLE " + TABLE_QUESTIONS + "(" + COLUMN_QUESTIONID + " integer primary key autoincrement, " 
     + COLUMN_QUESTION + " text not null, " 
     + COLUMN_EXPLANATION + " text not null, " 
     + COLUMN_QIMAGE + " text not null, " 
     + COLUMN_EIMAGE + " text not null, " 
     + COLUMN_MODULEID + " integer not null);"; 

private static final String OPTIONS_CREATE = "CREATE TABLE " + TABLE_OPTIONS + "(" + COLUMN_OPTIONID + " integer primary key autoincrement, " 
     + COLUMN_OPTION + " text not null, " 
     + COLUMN_CORRECTANSWER + " integer not null, " 
     + COLUMN_QUESTIONID + " integer not null);"; 

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

@Override 
public void onCreate(SQLiteDatabase database) { 
    database.execSQL(QUESTIONS_CREATE); 
    database.execSQL(OPTIONS_CREATE); 
} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    Log.w(DBHelper.class.getName(), 
      "Upgrading database from version " + oldVersion + " to " 
        + newVersion + ", which will destroy all old data"); 
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_QUESTIONS); 
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_OPTIONS); 
    onCreate(db); 
} 
} 

public class QuestionDataSource { 
private SQLiteDatabase database; 
private DBHelper dbHelper; 
private String[] allColumns = { DBHelper.COLUMN_QUESTIONID, DBHelper.COLUMN_QUESTION, DBHelper.COLUMN_EXPLANATION, 
    DBHelper.COLUMN_QIMAGE, DBHelper.COLUMN_EIMAGE, DBHelper.COLUMN_MODULEID }; 

public QuestionDataSource(Context context) { 
    dbHelper = new DBHelper(context); 
} 

public void open() throws SQLException { 
    database = dbHelper.getWritableDatabase(); 
} 

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

这是Helper为表问题

public Question createQuestion(String question, String explanation, String questionImage, String explanationImage, int moduleID) { 
    ContentValues values = new ContentValues(); 
    values.put(DBHelper.COLUMN_QUESTION, question); 
    values.put(DBHelper.COLUMN_EXPLANATION, explanation); 
    values.put(DBHelper.COLUMN_QIMAGE, questionImage); 
    values.put(DBHelper.COLUMN_EIMAGE, explanationImage); 
    values.put(DBHelper.COLUMN_MODULEID, moduleID); 
    long insertID = database.insert(DBHelper.TABLE_QUESTIONS, null, values); 

    Cursor cursor = database.query(DBHelper.TABLE_QUESTIONS, allColumns, DBHelper.COLUMN_QUESTIONID + " = " + insertID, null, null, 
      null, null); 
    cursor.moveToFirst(); 
    Question newQuestion = cursorToQuestion(cursor); 
    cursor.close(); 
    return newQuestion; 
} 

public List<Question> getAllQuestions() { 
    List<Question> questions = new ArrayList<Question>(); 
    Cursor cursor = database.query(DBHelper.TABLE_QUESTIONS, allColumns, null, null, null, null, null); 
    cursor.moveToFirst(); 
    while (!cursor.isAfterLast()) { 
     Question question = cursorToQuestion(cursor); 
     questions.add(question); 
     cursor.moveToNext(); 
    } 
    cursor.close(); 
    return questions; 
} 

private Question cursorToQuestion(Cursor cursor) { 
    Question question = new Question(); 
    question.setQuestionID(cursor.getInt(0)); 
    question.setQuestion(cursor.getString(1)); 
    question.setExplanation(cursor.getString(2)); 
    question.setQuestionImage(cursor.getString(3)); 
    question.setExplanationImage(cursor.getString(4)); 
    question.setModuleId(cursor.getInt(5)); 
    return question; 
} 
}

这是表选项

public class OptionDataSource { 
private SQLiteDatabase database; 
private DBHelper dbHelper; 
private String[] allColumns = { DBHelper.COLUMN_OPTIONID, DBHelper.COLUMN_OPTION, DBHelper.COLUMN_CORRECTANSWER, 
    DBHelper.COLUMN_QUESTIONID }; 

public OptionDataSource(Context context) { 
    dbHelper = new DBHelper(context); 
} 

public void open() throws SQLException { 
    database = dbHelper.getWritableDatabase(); 
} 

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

public Option createOption(String option, int correctAnswer, int questionID) { 
    ContentValues values = new ContentValues(); 
    values.put(DBHelper.COLUMN_OPTION, option); 
    values.put(DBHelper.COLUMN_CORRECTANSWER, correctAnswer); 
    values.put(DBHelper.COLUMN_QUESTIONID, questionID); 
    long insertID = database.insert(DBHelper.TABLE_OPTIONS, null, values); 
    Cursor cursor = database.query(DBHelper.TABLE_OPTIONS, allColumns, DBHelper.COLUMN_OPTIONID + " = " + insertID, null, null, 
      null, null); 
    cursor.moveToFirst(); 
    Option newOption = cursorToOption(cursor); 
    cursor.close(); 
    return newOption; 
} 

public List<Option> getAllOptions() { 
    List<Option> options = new ArrayList<Option>(); 
    Cursor cursor = database.query(DBHelper.TABLE_OPTIONS, allColumns, null, null, null, null, null); 
    cursor.moveToFirst(); 
    while (!cursor.isAfterLast()) { 
     Option option = cursorToOption(cursor); 
     options.add(option); 
     cursor.moveToNext(); 
    } 
    cursor.close(); 
    return options; 
} 

public List<Option> getOptions(int qID) { 
    List<Option> options = new ArrayList<Option>(); 
    String MY_QUERY = "SELECT * FROM options WHERE _questionid = " + qID + ";"; 
    Cursor cursor = database.rawQuery(MY_QUERY, null); 
    cursor.moveToFirst(); 
    while (!cursor.isAfterLast()) { 
     Option option = cursorToOption(cursor); 
     options.add(option); 
     cursor.moveToNext(); 
    } 
    cursor.close(); 
    return options; 
} 

private Option cursorToOption(Cursor cursor) { 
    Option option = new Option(); 
    option.setOptionID(cursor.getInt(0)); 
    option.setOption(cursor.getString(1)); 
    int cAnswer = cursor.getInt(2); 
    if (cAnswer == 0) { 
     option.setCorrectAnswer(false); 
    }else { 
     option.setCorrectAnswer(true); 
    } 
    option.setQuestionID(cursor.getInt(3)); 
    return option; 
} 
}

而这个帮手是MainActivity分类：

public class MainActivity extends ListActivity { 
private QuestionDataSource dataSourceQuestions; 
private OptionDataSource dataSourceOptions; 
ArrayList<String> listItems = new ArrayList<String>(); 
ArrayAdapter<String> adapter; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    dataSourceQuestions = new QuestionDataSource(this); 
    dataSourceQuestions.open(); 

    dataSourceOptions = new OptionDataSource(this); 
    dataSourceOptions.open(); 

    List<Question> questions = dataSourceQuestions.getAllQuestions(); 
    int qnCount = questions.size(); 
    for(Question qn : questions) { 
     TextView pregunta = (TextView) findViewById(R.id.textView1); 
     pregunta.setText(qn.getQuestion()); 
    } 
    for (int i = 0; i < qnCount; i++) { 
     listItems.add("Question " + (i + 1)); 
    } 
    listItems.add("Question 3"); 
    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, listItems); 
    setListAdapter(adapter); 
} 
@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    getMenuInflater().inflate(R.menu.activity_main, menu); 
    return true; 
} 

protected void onListItemClick(ListView l, View v, int position, long id) { 
    List<Question> questions = dataSourceQuestions.getAllQuestions(); 
    TextView pregunta = (TextView) findViewById(R.id.textView1); 
    pregunta.setText(questions.get(position).getQuestion()); 
    int questionID = questions.get(position).getQuestionID(); 
    setRadioButtons(questionID); 
} 

private void setRadioButtons(int questionID) { 
    List<Option> options = dataSourceOptions.getOptions(questionID); 

    RadioButton rdb1 = (RadioButton) findViewById(R.id.rdbOption1); 
    rdb1.setText(options.get(0).getOption()); 

    RadioButton rdb2 = (RadioButton) findViewById(R.id.rdbOption2); 
    rdb2.setText(options.get(1).getOption()); 

    RadioButton rdb3 = (RadioButton) findViewById(R.id.rdbOption3); 
    rdb3.setText(options.get(2).getOption()); 

    RadioButton rdb4 = (RadioButton) findViewById(R.id.rdbOption4); 
    rdb4.setText(options.get(3).getOption()); 
} 
}

如果有人能帮我解决这个问题，我将非常感激。再一次，我遇到的问题是它在模拟器上工作正常，但是当我在平板电脑上运行它（在平板电脑中安装.apk）时，它似乎不会读取数据库。

来源

2012-07-30 plasmy

该应用程序是否安装没有错误？ – javajavajava 2012-07-30 15:18:33

是的。事实上，如果你看到主要活动，你会发现我编写了“问题3”。它出现在平板电脑上，确认它确实没有读取数据库。 – plasmy 2012-07-30 16:53:26

我把插入查询放在onCreate而不是MainActivity中，它的工作完美。 – plasmy 2012-07-31 15:37:28

我把插入查询置于onCreate()而不是MainActivity，它的工作很完美。

来源

2012-09-11 20:17:33 plasmy

android数据库没有在平板电脑上阅读

回答

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