json

A very simple JSON parsing and stringifying library with defaults that I like.

There are many much more used and customizable libraries for this out there and if that is what you require you should use those libraries. This was initially built as an exercise for my brain, but it became complete and is now fairly fast and robust at doing what it does.

Some choices made, and why

• Numbers are parsed into as BigDecimals, it's the best fit for the JSON definition of a number and the only type of decimal value you should use in Java.
• Parsing is strict, e.g. ' is not allowed to define strings. It's a simple specification, it's not difficult to stay within it.
• Optionals are stringified as null or the object it contains. Since all fields in the resulting JSON objects basically behave as optional when used in JavaScript this seems like a good idea to me.
• Null values in objects are skipped when stringified. As above, null or undefined in JavaScript doesn't really matter which.
• Stringifying a parsed object removes all whitespace. I care about the data here, pretty printing is not really a concern.
• Reads a complete string and outputs a complete object. It does not read streams or output object events. Parsing a huge JSON stream where neither the input or the output fits in memory is an extreme edge case that should probably be avoided to begin with.
• Time objects like Instant, LocalDateTime, and so on are stringified as a string. Since browsers easily parse the format they output this seems like a good idea to me.
• No external runtime libraries. Since this began as an excercise for me I wanted to do it all. Also, simple things like this should not need any extra dependencies.

How to use

Add the dependency

<dependency>
    <groupId>com.grunka.json</groupId>
    <artifactId>json</artifactId>
    <version>1.10</version>
</dependency>

Stringify an object

String json = Json.stringify(Map.of("hello", "world")); 

Parse a JSON string

JsonValue value = Json.parse("{\"hello\":\"world\"}");

Parse a JSON string and map it into an object

record HelloRecord(String hello){}

HelloRecord who = Json.objectify("{\"hello\":\"world\"}", HelloRecord.class);

And more, see methods Json.objectifyMap, Json.objectifyList, Json.objectifySet, Json.valuefy, and Json.map.