How to deserialize a JSON file into an ArrayList with nested classes?

Question

I have this Java class:

class A {
    private B b;

    class B {
        private String a;
        //getter + setter
    }    
}

This is the content of JSON file:

[{"b" : {"a": "Hello!"}},
 {"b" : {"a": "Hi!"}},
 {"b" : {"a": "Hello2!"}}]

I want to deserialize my JSON file into an ArrayList<A> with the nested class inside. How can I do this?

Post some sample of JSON data as well. – anubhava Sep 21 '13 at 12:00 — anubhava, Sep 21 '13 at 12:00

score 1 · Accepted Answer · edited May 23 '17 at 11:50

You can simply achieve this with Gson.

package stackoverflow.questions.q18932252;

import java.lang.reflect.Type;
import java.util.*;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class Q18932252 {

    public static void main(String[] args){
        String json = "[{\"b\" : {\"a\": \"Hello!\"}}, {\"b\" : {\"a\": \"Hi!\"}}, {\"b\" : {\"a\": \"Hello2!\"}}]";
        Type listOfA = new TypeToken<List<A>>() {}.getType();
        Gson g = new Gson();
        ArrayList<A> result = g.fromJson(json, listOfA);
        System.out.println(result);


    }

}

With this result (I have added standard toString methods):

[A [b=B [a=Hello!]], A [b=B [a=Hi!]], A [b=B [a=Hello2!]]]

Since you are asking about a JSON file, ie a text file that contains a JSON string, please make reference to How to create a Java String from the contents of a file question for loading a file into a string.

score 0 · Answer 2 · edited May 23 '17 at 12:20

0

Refer to this post as per the information provided in the question this should solve your problem Json parsing with Gson with data and arrays

edited May 23 '17 at 12:20

Community

1
1

answered Sep 21 '13 at 12:04

Ravi

4,872
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This isn't the thing I was looking for, because I don't need to deserialize a json file with a array property inside the class, but I need to deserialize a json array of the whole class which contains a nested class. – Stein Dekker Sep 21 '13 at 12:11

score 0 · Answer 3 · answered Sep 21 '13 at 12:29

0

Using gson:

Gson gson = new Gson();
String json = "[{\"b\" : {\"a\": \"Hello!\"}}, {\"b\" : {\"a\": \"Hi!\"}}, {\"b\" : {\"a\": \"Hello2!\"}}]";
A[] arrA = new A[0];
System.out.println(Arrays.toString(gson.fromJson(json, arrA.getClass())));

answered Sep 21 '13 at 12:29

anubhava

761,203
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How to deserialize a JSON file into an ArrayList with nested classes?

3 Answers3