Parse only one field in a large JSON string

Question

I have a JSON string of the following format:

{

  \"foo\": \"small_vale\"  
  \"baz\": \"large_value\"
  \"bar\": \"another_large_value\"

}

H

Answer 1

Your json file is not valid. Commas are missing. It should look like this:

{
  "foo":"small_value",
  "baz":"large_value",
  "bar":"another_large_value"
}

This blog post says that Jackson or simple JSON are the fastest ways to parse big json data. Se the chapter "Big File Results" for reference.

Example code for Jackson: Jackson JSON – Read Specific JSON Key

It shows how to parse a json file ang get a value of a specific element.

//read json file data to String
byte[] jsonData = Files.readAllBytes(Paths.get("data.json"));

//create ObjectMapper instance
ObjectMapper objectMapper = new ObjectMapper();

//read JSON like DOM Parser
JsonNode rootNode = objectMapper.readTree(jsonData);
JsonNode fooNode = rootNode.path("foo");
System.out.println("foo value = "+fooNode.asText());