ferefrenzy.blogg.se - Android studio recyclerview remove itemtouchhelper

To detect whether the database contains data already, you can run a query to get one data item. In this task you update the app so that when it opens, the initial data set is only added if the database has no data. (Solution code for the previous practical is in GitHub.) This behavior isn't ideal, because users will want their added words to remain in the database when the app is closed. The RoomWordsSample app that you created in the previous practical deletes and re-creates the data whenever the user opens the app. Task 1: Initialize data only if the database is empty You also enable the user to swipe a word to delete it from the database.ģ. Then you add a menu item that allows the user to delete all the data. In this practical, you extend the app so that it only initializes the data in the database if there is no existing data. When the app closes and re-opens, the app re-initializes the database. So far, that app displays a list of words, and users can add words. You will extend the RoomWordsSample app that you created in the previous codelab. Optionally, in a coding challenge, extend the app to allow the user to update existing words.Allow users to delete a specific word by swiping an item in the list.Allow users to delete all words by selecting an Options menu item.Update the RoomWordsSample app to keep data when the app closes.How to update existing data (if you build the challenge app).

How to delete data from a Room database.

How to populate the database with data only if the database is empty (so users don't lose changes they made to the data).

You learned these topics in 10.1 Part A: Room, LiveData, and ViewModel.

Using entity classes, data access objects (DAOs), and the RoomDatabase to store and retrieve data in Android's built-in SQLite database.

In particular, be familiar with the following: You should be able to create and run apps in Android Studio 3.0 or higher. This codelab also includes a coding challenge, in which you update the app so the user can edit existing data. You will add the ability to delete specific items from the database. This codelab gives you more practice at using the API provided by the Room library to implement database functionality. This codelab (practical) follows on from 10.1 Part A: Room, LiveData, and ViewModel. Note: This course uses the terms "codelab" and "practical" interchangeably.

For details about the course, including links to all the concept chapters, apps, and slides, see Android Developer Fundamentals (Version 2).

For the complete list of codelabs in the course, see Codelabs for Android Developer Fundamentals (V2).

You will get the most value out of this course if you work through the codelabs in sequence: This practical codelab is part of Unit 4: Saving user data in the Android Developer Fundamentals (Version 2) course.