My json file is like this

  {
    "Parent1": {
    "Child1":"TRUE",
    "RandomKey":"TEST-111"
   },
     "Parent2": {
      "Child1":"TRUE",
     "AnotherRandomKey":"TEST-432"
    }
  }

My goal is to extract first occurrence of Child1 from either Parent1 or Parent2 depending on whatever exists, if both exists it should just get the first.

I have the following code written in java but it is always returning false. Not sure what i am doing wrong

   final var content = Jackson.getObjectMapper().readTree(//json link);

   Stream.concat(
         Optional.ofNullable(content.at("/Parent1/Child1")).stream(),
         Optional.ofNullable(content.at("/Parent2/Child1")).stream())
        .map(JsonNode::asBoolean)
        .filter(Objects::nonNull)
        .findFirst()
        .orElse(false);

I am trying to combine both streams and just find the first occurence of Child1 and return the boolean.

CodePudding user response：

The problem is that for some reason, JsonNode.asBoolean() is implemented to be case-sensitive. Hence, parses "TRUE" as false.

Method that will try to convert value of this node to a Java boolean. JSON booleans map naturally; integer numbers other than 0 map to true, and 0 maps to false and Strings "true" and "false" map to corresponding values.

It's not very intuitive because standard JDK wrapper type Boolean performs parsing in the case-insensitive manner.

As a workaround, we can extract a String from a node, and then apply Boolean.parseBoolean.

Note: there's no need to create an Optional in order to generate a stream. In this case, Optional.ofNullable(content.at()) is an abuse of optional (for more details on the usage of optional see).

We can use Stream.of() for that purpose.

public static void main(String[] args) throws JsonProcessingException {
    String message = """
        {
            "Parent1": {
            "Child1":"TRUE",
                "RandomKey":"TEST-111"
        },
            "Parent2": {
            "Child1":"TRUE",
                "AnotherRandomKey":"TEST-432"
        }
        }""";
    
    ObjectMapper mapper = new ObjectMapper();
    JsonNode content = mapper.readTree(message);
    
    boolean result = Stream.of(content.at("/Parent1/Child1"), content.at("/Parent2/Child1"))
        .filter(Objects::nonNull)
        .map(JsonNode::asText)
        .map(Boolean::parseBoolean)
        .filter(value -> value) // guarding against the case when node "Parent1" doesn't exist
        .findFirst()
        .orElse(false);

    System.out.println(result);
    
}

Output:

true