What is Room Database in Android

INTRODUCTION

• Room is a constant library that is part of the Android jetpack. It is built On the top of SQLite. The room persistent library has many advantages over raw SQLite.

• Room is one of the Jetpack Architecture Components in Android. This provides an abstract layer over the SQLite. 

• Room makes everything easy and clear to create a Database and achieve the operations on it.

• Database to save and perform the operations on endless data locally. The Room DataBase is suggested by Google over SQLite.

• It can help to manage data. 

WHY USE ROOM?

• Cache the applicable pieces of the data so that when the user’s device is offline, they can still browse and aspect the content offline.
• Compile-time SQLite query verification protects the application from collision.
• The comment that it gives minimises the boilerplate code.

CONDITIONS IN ROOM DATABASE-

• Have Android Studio installed.
• Have a basic knowledge of building Android applications.
• Have a basic understanding of the Kotlin programming language, SQL, MVVM architecture and Kotlin coroutines.

KEY POINTS OF ROOM DATABASE–

• No need to write rough Queries.
• Compile Time verification of SQL queries.
• This quickly supports the merging with other Architecture components.
• Room provides an easier way to work with LiveData and perform the operations.
• There is no need to change the code when the database schema gets changed.

PRIMARY COMPONENTS OF ROOM–

• Database Class: This provides the main access point to the basic connection for the application’s persisted data. This is annotated with @Database.
• Data Entities: This represents all the tables in the existing Database. This is annotated with @Entity.
• DAO: It stands for DATA ACCESS OBJECT. This contains the method to perform the operations on the Database. This is annotated with @DAO.

• @Insert-It  is Used to insert records into the Room Database.
• @Delete-It is Used to delete records into the Room Database.
• @Update-It is Used to update records in the Room Database.
• @Query-It is Used to enter the Query like(SELECT FROM).

Steps to implement Room Database in Android Application-

Step 1: Create an Empty Activity project

• Firstly We can Create an empty Android Studio project. Create/Start a New Project in Android Studio.

Step 2: Adding the Required Dependencies

• Then We Can Add the dependencies to the app-level gradle file. By going to ProjectName -> src -> build. gradle.

Step 3: Creating Data Entity

• Create a Sample Data class named User. kt.
• And call on the code which contains entities User as an entity, which represents a row and first_name, last_name, and age represent column names of the table.

Step 4: Creating Data Access Objects (DAOs):

• Now create an interface named UserDao.kt.
• And call on the code which provides various methods which are used by the application to interact with the user.

Step 5: Creating the Database

• Now creating the Database which defines the real application’s database, which is the main access point to the application’s continuous data. This class must satisfy:

•  The class must be abstract.
•  The class should be annotated with @Database.
•  Database class must define an abstract method with zero arguments and return a case of DAO.

• Now call on the code inside the AppDatabase.kt file.

Step 6: Usage of the Room Database

• Inside the MainActivity.kt file we can create a database, by providing usage names for the database.