JsonNode — Core Type Reference

JsonNode is the sealed base interface for all JSON elements.

Type Hierarchy

JsonNode (sealed)
├── JsonObject   → {"key": value, ...}
├── JsonArray    → [elem, elem, ...]
└── JsonValue    → "string", 42, 3.14, true, false, null

Type Checks

node.isObject()   // true if JsonObject
node.isArray()    // true if JsonArray
node.isValue()    // true if JsonValue
node.isNull()     // true if value is JSON null
node.isString()   // true if String leaf
node.isNumber()   // true if Number leaf
node.isBoolean()  // true if Boolean leaf

Value Extraction

Method	Returns	Default
asText()	String	"null"
asText("default")	String	given default
asInt()	int	0
asInt(defaultValue)	int	given default
asLong()	long	0L
asDouble()	double	0.0
asBigDecimal()	BigDecimal	ZERO
asBoolean()	boolean	false

Child Access

// By key (objects)
JsonNode child = node.get("name");

// By index (arrays)
JsonNode elem  = node.get(0);

Path Navigation

Optional<JsonNode> val = node.find("store.books[0].title");
val.ifPresent(t -> System.out.println(t.asText()));

Supports:

• Dot separation: "user.address.city"
• Array index: "items[2]"
• Combined: "store.books[0].author.name"

Find All (Deep Search)

// Find every node with key "price" anywhere in the tree
List<JsonNode> prices = node.findAll("price");

Deep Equality

boolean same = node1.deepEquals(node2);  // structural comparison

Size

node.size();
// JsonObject  → field count
// JsonArray   → element count
// JsonValue   → always 1