mjson - Minimalistic JSON Library

News

• October 5, 2024 - 1.4.2 released after a long hiatus. Fixes memory leak problem, a security vulnerability and doc lint warnings during build.

What Is It?

mJson is an extremely lightweight Java JSON library with a very concise API. The source code is a single Java file. The license is Apache 2.0. Because of its tiny size, it's well-suited for any application aiming at a small footprint such as mobile/Android applications.

It was originally developed in the context of the OpenCiRM project. There is a graph database based persistent layer for mJson implemented at the HyperGraphDB Project. This means you can transparently persist and query JSON documents like in document-oriented databases (MongoDB, CouchDB), but you don't have split documents into separate collection or create special purposes indices since all documents and properties are automatically interlinked.

Features

• Full support for JSON Schema Draft 4 validation
• Single universal type - everything is a Json, no type casting
• Single factory method, no new operators, just call Json.make(anything here)
• Fast, hand-coded parsing
• Designed as a general purpose data structure for use in Java
• Parent pointers and up method to traverse the JSON structure
• Concise methods to read (Json.at), modify (Json.set, Json.add), duplicate (Json.dup), merge (Json.with)
• Methods for type-check (e.g. Json.isString()) and access to underlying Java value (e.g. Json.asString())
• Method chaining
• Pluggable factory to build your own support for arbitrary Java<->Json mapping
• 1 Java file is the whole library with no external dependencies

API Tour

Go see a Complete Tour of the API

Read my tutorial blog on JSON Schema

Wish List

(get in touch if you want to help!)

1. Traversal API, with pattern-matching
2. Extend JSON Schema support for template generation

Goto mJson Official Website