JSON to Object conversion in Java

Question

Lets take a example my object Person having 2 properties below

public class Person {

    String name;
    Integer age;

    //getters and setters
}

but jsonaray contains more than 2 properties

[{
    "name": "ab",
    "age": 18,
    "c": "dc",
    "d": "ef"
}]

Here extra elements c and d are there. Can I convert that jsonarray to set person object?

Also, what do you want to happen to the extra elements c and d? — Joni, Jul 17 '20 at 12:46
Btw, your JSON is invalid. There should be no "," after "d":"ef" — Nishit, Jul 17 '20 at 12:48
@Nishit, Thanks i updated my json and yes i want to ignore c and d — vinay kumar, Jul 17 '20 at 13:01

score 3 · Accepted Answer · edited Jul 17 '20 at 13:12

3

Since we don't know which library you are using, I would go ahead and assume you are using the most common one - Jackson.

Use @JsonIgnoreProperties(ignoreUnknown = true) annotation on your Person class. This annotation allows you to ignore any field in the JSON which doesn't map to the fields in your POJO.

edited Jul 17 '20 at 13:12

daniu

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answered Jul 17 '20 at 13:09

Nishit

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score 1 · Answer 2 · answered Jul 17 '20 at 13:18

You have got multiple options

Code a JSON Parse your self(Which I hope is not the expectation here).
Use frameworks/JSON parser libraries available.

One such framework is jackson. You can achieve what you need as below

public static void main(String[] args) throws Exception {

   //Step 1. Create and set properties of ObjectMapper.
   // You need FAIL for unknow properties false for your case
   ObjectMapper mapper = new ObjectMapper();
   mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
       
   String jsonStr = {
                    "name": "ab",
                    "age": 18,
                    "c": "dc",
                    "d": "ef"
                   };
       try{
            //Step 2: call mapper to convert it to your class
            Person person = mapper.convertValue(jsonStr, Data.class);
        }catch(IllegalArgumentException e){
            //log error
        }
}

JSON to Object conversion in Java

2 Answers2