A Simple Android Project Demonstrating Persistence of Inter-Related Objects Using JDXA ORM
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A Simple Android Project Demonstrating Persistence of Inter-Related Objects Using JDXA ORM

This project shows a simple Android app using JDXA ORM to exchange data of the inter-related objects with an on-device SQLite relational database. The object model used by this app has one-to-one and one-to-many relationships. A company has many departments and many foreign locations. An employee has an address and works in a department.

JDXA Relationships Picture

Some highlights:

  • The object model consists of five inter-related POJO classes (SimpleCompany, SimpleDept, SimpleForeignLocation, SimpleEmp, and SimpleAddr):
    • SimpleEmp has a one-to-one relationship with SimpleDept and another one-to-one relationship with SimpleAddr.
    • SimpleCompany has a one-to-many relationship with SimpleDept and another one-to-many relationship with SimpleForeignLocation.
  • The declarative mapping specification (in the file .../res/raw/relationships_example.jdx) is simple, intuitive, non-intrusive, and succinct.
  • Easy mechanism for preloading the database with new objects at the time of database creation.
  • API calls for CRUD operations are simple. They show the following features:
    • Deep query, Shallow query, Named query
    • Directed query, Lazy loading, Auto primary-key
  • JDXA provides handy utility methods for displaying an object or a list of objects.

This project is also presented in a video format on YouTube at https://youtu.be/VBAEsgdi5pU (Part 1) and at https://youtu.be/1-2aE5ZI_rY (Part 2)

To run this app in your own setup, please do the following:

  • Clone this project on your desktop.
  • Get the JDXA SDK download instructions from this link.
  • You may download just the mini version of the SDK.
  • Add the libraries (JDXAndroid-nn.n.jar and sqldroid.jar) from the SDK to the app/libs directory and build the project.
  • Run the app.


JDXA is a simple yet powerful, non-intrusive, flexible, and lightweight Object-Relational Mapping (ORM) product that simplifies and accelerates the development of Android apps by providing intuitive, object-oriented access to on-device relational (e.g., SQLite) data.

Adhering to some well thought-out KISS (Keep It Simple and Straightforward) principles, JDXA boosts developer productivity and reduces maintenance hassles by eliminating endless lines of tedious SQL code.

Some of the powerful and practical features of JDXA include:

  • Declarative mapping specification between an object model and a relational model is done textually using a simple grammar (no XML complexity).

  • Full flexibility in domain object modeling – one-to-one, one-to-many, and many-to-many relationships as well as class-hierarchies supported.

  • POJO (Plain Old Java Objects) friendly non-intrusive programming model, which does not require you to change your Java classes in any way:

    • No need to subclass your domain model classes from any base class
    • No need to clutter your source code with annotations
    • No source code generation (No need for DAO classes)
    • No pre-processing or post-processing of your code
  • Support for persistence of JSON objects.

  • A small set of intuitive APIs for object persistence.

  • Automatic generation of relational schema from an object model.

  • A highly optimized metadata-driven ORM engine that is lightweight, dynamic, and flexible.

JDXA ORM is a product of Software Tree. To get more information and a free trial version of JDXA SDK, please visit http://www.softwaretree.com.

JDXA is used with the SQLDroid open source library. SQLDroid is provided under the licensing terms mentioned here.