java.lang.StringIndexOutOfBoundsException:在= sqlite数据库中索引= 0 length = 0

Question

我试图用这段代码打开一个可写的SQLite数据库......

public DataAdapterForServieClass open() throws SQLException {
    db = DBHelper.getWritableDatabase();
    return this;
}

但是我在线上收到以下错误db = DBHelper.getWritableDatabase();...

06-10 11:58:13.995: ERROR/AndroidRuntime(548): FATAL EXCEPTION: main
06-10 11:58:13.995: ERROR/AndroidRuntime(548): java.lang.StringIndexOutOfBoundsException: index=0 length=0
06-10 11:58:13.995: ERROR/AndroidRuntime(548):     at android.app.ContextImpl.validateFilePath(ContextImpl.java:1518)
06-10 11:58:13.995: ERROR/AndroidRuntime(548):     at android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:725)
06-10 11:58:13.995: ERROR/AndroidRuntime(548):     at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:221)
06-10 11:58:13.995: ERROR/AndroidRuntime(548):     at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:149)

这是我DBHelper班的代码......

static class DatabaseHelper extends SQLiteOpenHelper {
    DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

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

    public void onCreate(SQLiteDatabase arg0) {
        // TODO Auto-generated method stub
    }
}   

有人可以帮帮我吗

Answer 1

当你getWritableDatabase()第一次调用时，它会调用以下方法，根据Android文档...

onCreate(SQLiteDatabase)
onUpgrade(SQLiteDatabase, int, int)
onOpen(SQLiteDatabase)

您的方法中没有任何代码onCreate()- 您需要在它起作用之前在这里做一些事情，例如这样......

public void onCreate(SQLiteDatabase database) {
    database.openOrCreateDatabase("/come/example/mydatabase",null);
}

查看您发布的链接checkDataBase()中调用的方法- 这做同样的事情，并且是您缺少的重要代码片段。您需要先创建数据库，然后才能对其执行任何操作。openDatabase()

还要确保在代码中的某个位置创建 DBHelper 实例，以便它调用该super()方法。像这样...

DBHelper helper = new DatabaseHelper(context);