Efficiently find a key-value in JSON with JAVA

Question

I want to find whether a key-value pair exists in a JSON given a key. This key-value pair may not be under root. It's possible embedded deeply in the document. For example:

{"Persons":[
  {"Person":
    {"name":"john"}
  }]
}

and I want to have something like JsonDoc.has("name"), and return true. I search online and find this thread: Java: Json has key/field

Two answers (minimal-json and org.json) both has some functioned called has() or get(), but I looked into their source code, they are both trying to find the key-value under root. So they don't meet my needs.

I can think of traversing the whole json and try to find the key-value, but it seems not efficient.

How do you expect to search the whole tree without searching the whole tree (traversing it)? — ikegami
– ikegami, Commented Jul 9, 2015 at 22:16
So... I'm looking for a good algorithm, or a library that has already implement some algorithm for me. Hopefully later one... — pythonician_plus_plus
– pythonician_plus_plus, Commented Jul 9, 2015 at 22:28

habsq · Accepted Answer · 2015-07-11 01:41:48Z

1

If you use Jackson, you can call findParent on a JsonNode which will look for a field within the node or its descendant.

http://fasterxml.github.io/jackson-databind/javadoc/2.2.0/com/fasterxml/jackson/databind/JsonNode.html#findParent(java.lang.String)

answered Jul 11, 2015 at 1:41

habsq

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