JAVA : How Map JSON key value pair to different variables Jackson

Question

How to map the following json to a classB object using Jackson

JSON Input

{"pattern":3,"graphs":4}

Class A

class ClassA{
String name;
int count;
}

Class B

class ClassB{
Set<ClassA> data;
}

Answer 1

Assuming you have a constructor in ClassA as follows:

class ClassA {
    String name;
    int count;

    public ClassA(String name, int count) {
        this.name = name;
        this.count = count;
    }
}

You can use @JsonCreator to fine tune the constructor or factory method used in the deserialization as follows:

class ClassB {
    Set<ClassA> data;

    @JsonCreator
    public ClassB(Map<String, Integer> data){
        this.data = data.entrySet().stream()
                .map(entry -> new ClassA(entry.getKey(), entry.getValue()))
                .collect(Collectors.toSet());
    }
}