JSON Wheel

Have you ever written scripts in Java 11+ and needed to operate on some JSON string? Have you ever needed to extract just that one deeply-nested value of an application/json response without modelling the whole hierarchy? Have you ever felt someone should indeed reinvent that wheel and provide the JVM universe with yet another JSON deserializer?

If the answer to any of those is "yes", then look no further, JSON Wheel's got you covered.

It's a 250 lines single-source-file hackable JSON deserializer written in plain Java.

If the answer is "no": Fine by me, I still had fun writing the thing. :)

Features

very small codebase
hackable
dependency-less
compatible to JDK 8+
not toooo slow

Limitations

deserialization-only
not typed, except for the WheelNode type (which you may cast to "value" types, see below)
Java number types currently offered: Double, BigDecimal, Integer, Long, BigInteger
only partially safe against malformed input

Usage

Within Your Script

Copy the content of the most recent version of JsonWheel.java as-is into your existing script.
Remove imports if colliding with your pre-existing ones.

Within Your Project

Copy the most recent version of JsonWheel.java as a file into your project's source directory, e.g. /src/main/java.
Adjust the package declaration, i.e. introduce one, if needed.

With JBang's `//SOURCES`

Create a JBang script, e.g. with jbang init.
Add the //SOURCES JBang directive, as demonstrated here. If you care for your script to not break, you best set a version directly in the link and don't use the main blob.

Then you can ...

1) Deserialize JSON objects

var json = """
    {
        "foo": 1,
        "bar": "baz",
        "qux": null
    }""";

var node = JsonWheel.read(json);
var foo = node.get("foo").val(Integer.class); // 1
var bar = node.get("bar").val(String.class);  // "baz"
var qux = node.get("qux").val(String.class);  // null

2) Deserialize JSON arrays

var json = """
    [
        1,
        2,
        3
    ]""";

var node = JsonWheel.read(json);
var list = node.elements()
        .stream()
        .map(e -> e.val(Integer.class))
        .toList();  // 1 2 3

3) Deserialize "complex" JSON

var json = """
    {
        "foo": {
            "bar" : [
                1,
                2,
                3
            ],
            "baz": "qux"
        }
    }""";

var node = JsonWheel.read(json);
var bar = node.get("foo").get("bar").elements()
        .stream()
        .map(e -> e.val(Integer.class))
        .toList(); //   1 2 3
var baz = node.get("foo").get("baz").val(String.class); //  "qux"

enr/jsonwheel