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Android Android Data Persistence CRUD Operations with SQLite Deleting Data

Posted by Unsubscribed User
Unsubscribed User
12,721 Points

Why "%s=%s" in the String.format(..) method?

In this video, why has Evan Anger used the format "%s=%s" for ID values where an additional data type conversion was required (from int to String) instead of using the format "%s=%d" like in the previous cases?

1 Answer

Harry James
Harry James
14,780 Points
Harry James
Harry James
14,780 Points

I believe Evan was just showing an alternate method of doing this.

If you were to change your code to

        database.delete(MemeSQLiteHelper.ANNOTATIONS_TABLE,
                String.format("%s=%d", MemeSQLiteHelper.COLUMN_FOREIGN_KEY_MEME,
                        memeId), null);
        database.delete(MemeSQLiteHelper.MEMES_TABLE,
                String.format("%s=%d", BaseColumns._ID,
                        memeId), null);

then it would also work fine.

However, this would not work:

        // ** ** ** This would cause an error because the second parameter is not a String (%s) ** ** **
        database.delete(MemeSQLiteHelper.ANNOTATIONS_TABLE,
                String.format("%s=%s", MemeSQLiteHelper.COLUMN_FOREIGN_KEY_MEME,
                        memeId), null);
        database.delete(MemeSQLiteHelper.MEMES_TABLE,
                String.format("%s=%s", BaseColumns._ID,
                        memeId), null);

or this:

        // ** ** ** This would cause an error because the second parameter is not a integer/decimal (%d) ** ** **
        database.delete(MemeSQLiteHelper.ANNOTATIONS_TABLE,
                String.format("%s=%d", MemeSQLiteHelper.COLUMN_FOREIGN_KEY_MEME,
                        String.valueOf(memeId)), null);
        database.delete(MemeSQLiteHelper.MEMES_TABLE,
                String.format("%s=%d", BaseColumns._ID,
                        String.valueOf(memeId)), null);

I can understand the confusion this could cause but, as long as you understand that the formatters have to match the parameters, it doesn't matter what you put :)