ArrayNode.get() I'm accessing a null value or I'm out of bound?

[rigazilla]

How can I distinguish if I'm accessing a null element or the index is out of bound?

What's the reason why ArrayNode.get() returns null on out of bound index?

jackson-databind/src/main/java/tools/jackson/databind/node/ArrayNode.java

Lines 221 to 226 in 961c128

	public JsonNode get(int index) {
	if ((index >= 0) && (index < _children.size())) {
	return _children.get(index);
	}
	return null;
	}

[cowtowncoder]

Null elements are represented as non-null NullNodes, so JsonNode.isNull().

Or, if you don't want null checks, ArrayNode.path(int) never returns null but returns:

1. NullNode if within Array value, JSON null value
2. MissingNode if outside array (index out-of-bounds)

As to why null: design choice, to work similar to ObjectNode.get(String) for key that does not match any property; returns null.

[rigazilla]

Thanks for your prompt answer, I can see the rational.

I've also found where my problem really is.
I'm working with Jsonpath (JacksonJsonNodeJsonProvider) and I've set it to return results as a list and what happens is:

• jsonpath read the array and gets null or NullNode (depending on the case)
• creates a ArrayNode and adds the read result to it
• unfortunately ArrayNode.add() wraps null into NullNode
• this makes my code unhappy

jackson-databind/src/main/java/tools/jackson/databind/node/ArrayNode.java

Lines 445 to 450 in 961c128

	public ArrayNode add(JsonNode value)
	{
	if (value == null) { // let's not store 'raw' nulls but nodes
	value = nullNode();
	}
	_add(value);

well I think I agree that ArrayNode should contain only JsonNode, maybe the integration needs a fix

[cowtowncoder]

Ok that makes sense. Thank you for background @rigazilla .