sola-json

SolaJson is a lightweight JSON parsing library for Java 17+ that uses no additional libraries internally. It started as a project to continue learning about building parsers based on language grammars.

Parser definition based on json.org

Download

Gradle + Jitpack:

repositories {
    maven {
        url = uri("https://jitpack.io")
    }
}

dependencies {
    implementation("com.github.iamdudeman:sola-json:2.1.3")
}

sola-json jar downloads hosted on GitHub releases.

Example usages

Basic Usage

public class BasicUsage {
    public static void main(String[] args) {
        String jsonString = """
            {
              "key": "value"
            }
            """;
        SolaJson solaJson = new SolaJson();
        JsonObject root = solaJson.parse(jsonString).asObject();
        System.out.println(root.getString("key"));

        root.put("key2", 10);
        System.out.println(solaJson.stringify(root));
    }
}

# Output
value
{"key":"value","key2":10}

Usage with JsonMapper

public class JsonMapperUsage {
    public static void main(String[] args) {
        String input = """
            {
              "value": 1
            }
            """;
        SolaJson solaJson = new SolaJson();
        Pojo result = solaJson.parse(input, JSON_MAPPER);
        System.out.println(result.value());

        Pojo pojo = new Pojo(10);
        System.out.println(solaJson.stringify(pojo, JSON_MAPPER));
    }

    public record Pojo(int value) {
    }

    static JsonMapper<Pojo> JSON_MAPPER = new JsonMapper<>() {
        @Override
        public JsonObject toJson(Pojo object) {
            JsonObject jsonObject = new JsonObject();

            jsonObject.put("value", object.value());

            return jsonObject;
        }

        @Override
        public TestPojo toObject(JsonObject jsonObject) {
            return new Pojo(jsonObject.getInt("value"));
        }
    };
}

# Output
1
{"value":1}

Terminals

COLON      := :
COMMA      := ,
FALSE      := false
L_BRACKET  := [
L_CURLY    := {
NULL       := null
NUMBER     := ((-[1-9])|0)[0-9]+(.[0-9]+)?([eE][-+]?[0-9]+)
R_BRACKET  := ]
R_CURLY    := }
STRING     := " (Any codepoint except " or \ or control characters) "
TRUE       := true

Rules

<root>    := <object> | <array>
<object>  := L_CURLY (<pair> (COMMA <pair>)*)? R_BRACKET
<array>   := L_BRACKET (<value> (COMMA <value>)*)? R_BRACKET
<pair>    := STRING COLON <value>
<value>   := STRING | NUMBER | <object> | <array> | TRUE | FALSE | NULL