尝试重新打开已经关闭的对象:sqlitequery

Question

所以基本上我两次查询数据库.我不明白这个错误究竟来自哪里,因为我没有在任何地方关闭数据库.返回错误的代码就是这样运行的.我查了一下,我刚看到像我这样的案子.

BeaconHandler pullAllDB = new BeaconHandler(this);
    try {
        List<Beacon> beaconsShown = pullAllDB.getAllBeacons();
        for (final Beacon bn : beaconsShown) {
            try {
                int messageCount = pullAllDB.getMessageCount();
                Log.d("Message", messageCount + " Messages Found");
                if (messageCount > 0) {
                    //Do Something
                } else {
                    // Do Nothing
                }
            } 
            catch (Exception e) {
                e.getStackTrace();
                Log.e("Message", e.getMessage());
            }
        }
    }

以及执行查询的代码......

public int getBeaconsCount() {

    String countQuery = "SELECT * FROM " + TABLE_BASIC_BEACON;
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery(countQuery, null);
    cursor.close();

    // return count
    return cursor.getCount();

}

public int getMessageCount() {

    String mcountQuery = "SELECT * FROM " + MESSAGE_BEACON;
    SQLiteDatabase mdb = this.getReadableDatabase();
    Cursor mcursor = mdb.rawQuery(mcountQuery, null);
    mcursor.close();

    // return count
    return mcursor.getCount();

}

Answer 1

如果收到错误,您应该发布一个logcat.它有助于查看导致问题的线路.

来自Android文档.

关()

关闭Cursor,释放所有资源并使其完全无效.

mcursor.getCount()关闭它后,您的来电可能会导致错误

也许尝试这样的事情.

int count = mcursor.getCount();
mcursor.close();

// return count
return count ;