android - 我想使用 SQLiteOpenHelper 创建一个数据库，但我遇到了一些问题

Question

我创建了一个 SQLiteOpenHelper 类的子类 (DatabaseHelper)。它有一个构造函数和两个重写的方法

 public DatabaseHelper(Context context) {
            super(context, dbName, null,33);
            // TODO Auto-generated constructor stub
        }
public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        db.execSQL("CREATE TABLE "+ quizTable +"("+quizCol1+" INTEGER PRIMARY KEY,"+
                quizCol2+" TEXT,"+ quizCol3 +" TEXT,"+ quizCol4 +" INTEGER," + quizCol5 + " DATETIME )");

        db.execSQL("CREATE TABLE "+ questionTable +"("+questionCol1+" INTEGER PRIMARY KEY,"+
                questionCol2+" INTEGER,"+ questionCol3 +" TEXT,"+ questionCol4 +" TEXT," + questionCol5 + " TEXT," +
                questionCol6 + " TEXT," + questionCol7 +" TEXT," + questionCol8 +" TEXT)");

        db.execSQL("CREATE TABLE "+ playedQuizzes +"("+playedQuizCol1+" INTEGER PRIMARY KEY,"+
                playedQuizCol2+" TEXT,"+ playedQuizCol3 +" TEXT,"+ playedQuizCol4 +" TEXT," +
                playedQuizCol5 + " TEXT)");
        System.out.println("this is onCreate method");
        InsertQuiz();
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
        db.execSQL("DROP TABLE IF EXISTS "+questionTable);
        db.execSQL("DROP TABLE IF EXISTS "+playedQuizzes);

        onCreate(db);
    }

在我的 Activity 子类中，我使用

调用了上述类的构造函数

 public void onStart(){
        try{
            super.onStart();
             dbHelper = new DatabaseHelper(this);
        }catch(Exception ex){
            CatchError(ex.toString());
        }       
    }

但是当我运行我的 Activity 类并打开我的 DDMS 透视图时，我没有找到在/data/data/下创建的任何数据库

我的知识或代码有问题吗？如果是，请告诉我。

Answer 1

在你的代码中你没有打开数据库....

创建、写入或打开数据库 getWritableDatabase()

或者创建和打开数据库 getReadableDatabase() 是必需的......