计算数据库中所有行的方法会使我的应用程序崩溃

您试图获取游标计数,但上面的行关闭了与数据库的连接。您应该先获得计数,然后关闭连接,如:

public int getDBPlacesCount() {
        String countQuery = "SELECT  * FROM " + TABLE_DB_VERLADESTELLEN_Eintrag;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        int count = cursor.getCount();
        cursor.close();

        // return count
        return count
    }

read 从已经存在的光标 closed ,这是错误的。

您需要更改代码,如下所示:

public int getDBPlacesCount() {
    try {
        String countQuery = "SELECT  * FROM " + TABLE_DB_VERLADESTELLEN_Eintrag;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        long count = cursor.getCount();

        // return count
        return count;
     } catch(SQLException exe) {
        //log exceptions
     } finally {
       if(cursor != null) {
          //always close the cursor in finally and make it null
          cursor.close();
          cursor = null;
       }
     }
}

此外,请确保在 finally 堵塞以避免泄漏。