Android Room vs GreenDAO: What are the differences?

Introduction

In this article, we will compare Android Room and GreenDAO, two popular technologies used in Android app development for managing local databases. We will explore their key differences to help developers make an informed decision on which one to choose for their projects.

1. Database Framework Architecture: The architecture of Android Room is built on top of SQLite, the same powerful and widely-used database engine. It provides a layer of abstraction that simplifies database operations and reduces the amount of boilerplate code. GreenDAO, on the other hand, uses an Object Relational Mapping (ORM) approach to map Java objects to database structures. It provides a more object-oriented way of working with databases.

2. Annotation-based Development: Android Room heavily relies on annotations to define database entities, queries, and relationships. It uses annotations like @Entity, @Dao, and @Query for defining the structure of the database and performing queries. GreenDAO also utilizes annotations, but with a different set of annotations like @Entity, @ToMany, and @ToOne. Developers need to understand and use the specific annotations provided by each library.

3. Code Generation: Android Room includes a code generation feature that generates necessary code at compile-time, based on the annotations used. This means that developers can focus on writing concise and manageable code, while Room takes care of the boilerplate code. GreenDAO also utilizes code generation, but it requires developers to manually trigger the generation process.

4. Queries and Relationships: Android Room offers the power of SQL queries and supports complex relationships between entities, making it suitable for more advanced use cases. It allows developers to write custom queries using SQL or use its built-in query generation capabilities. GreenDAO, on the other hand, provides a simpler approach to querying the database by using its own fluent API and does not support complex relationships out of the box.

5. Integration with LiveData and RxJava: Android Room is designed to work seamlessly with LiveData, a lifecycle-aware data holder, making it straightforward to observe and react to changes in the database. It also provides support for RxJava, allowing developers to use reactive programming patterns. GreenDAO does not have built-in support for LiveData or RxJava and requires additional workarounds to achieve similar functionality.

6. Migrations and Schema Management: Android Room simplifies the process of database versioning and schema management by offering built-in support for schema migrations. Developers can easily update the database schema without losing data or requiring manual intervention. GreenDAO, on the other hand, does not provide built-in migration support and requires developers to handle schema changes manually.

In summary, Android Room and GreenDAO have distinct approaches to managing local databases in Android apps. Android Room offers a modern, annotation-based approach with code generation, advanced query capabilities, and integrated support for LiveData and RxJava. On the other hand, GreenDAO provides a simpler ORM-based solution, with its own query API, and requires manual code generation and schema management. Developers should consider their project requirements and preferences to choose the most suitable database management solution.