CODEWITHSUNDEEP
javaandroidjsonretrofit2pojo
shuetisha.dev
shuetisha.dev

Reputation: 109

What is the proper way of handling multiple JSON Objects with Retrofit 2?

I am trying to parse a JSON URL with Retrofit 2 for my Android project and I have a question. In my URL the JSON look like this:

{  
"channel0":{  
  "song":"Crush",
  "artist":"Jennifer Paige",
  "duration":"180",
  "playedat":"1545065265",
  "image_extralarge":"https:\/\/lastfm-img2.akamaized.net\/i\/u\/300x300\/8eecc92227fcbb09b43472f000df74e1.png"
},
"channel1":{  
  "song":"Reasons Why",
  "artist":"Brand New Immortals",
  "duration":"180",
  "playedat":"1545065371",
  "image_extralarge":"https:\/\/lastfm-img2.akamaized.net\/i\/u\/300x300\/c059afda95dd35354af26cf72e5deab4.png"
},
"channel2":{  
  "song":"Dance Me To The End Of Love",
  "artist":"Leonard Cohen",
  "duration":"300",
  "playedat":"1545065181",
  "image_extralarge":"https:\/\/lastfm-img2.akamaized.net\/i\/u\/300x300\/a368617dc7dc4716a9badb523ff6e7d4.png"
},
"channel3":{  
  "song":"4 Minutes",
  "artist":"Madonna",
  "duration":"180",
  "playedat":"1545065300",
  "image_extralarge":"https:\/\/lastfm-img2.akamaized.net\/i\/u\/300x300\/1dcefc6496be4155a00f919dcbb54f77.png"
},
"channel4":{  
  "song":"Mothers, Sisters, Daughters",
  "artist":"Voxtrot",
  "duration":"180",
  "playedat":"1545065257",
  "image_extralarge":"https:\/\/lastfm-img2.akamaized.net\/i\/u\/300x300\/5861b97231bd4ffe9218dfcacc27d68a.png"
}
}

And when I use POJO, it creates multiple classes for every channel. So what is the proper way of handling this JSON URL?

Upvotes: 1

Views: 1425

Answers (2)

Rafael Lima
Rafael Lima

Reputation: 3535

First: this is not called JSON URL... it's simple JSON, or JSON data if you want... URL and JSON are two totally separated things

Second: is not clear what you mean when you say:

And when I use POJO, it creates multiple classes for every channel. So what is the proper way of handling this JSON URL?

If you are generating Java classes from any JSON to POJO tool this is a normal behavior since no tool has how to guess that channel2 is the same thing as channel3 as JSON instances they can be two totally different things, there is no way to know.

The right way is to design your Java classes first and then map the JSON, not the opposite.

Upvotes: 0

Ben P.
Ben P.

Reputation: 54204

Every JSON object can also be considered a Map of strings to JSON elements. In cases like this, where you're going to get an object with dynamic key names, you don't have to try to build a Java class to represent it. You can just use Map<String, Object> instead.

In this case, you know that each value will be a song, so you can be a little more specific than Object.

Start by defining e.g. a Song class to hold the inner elements:

public class Song {

    public String song;
    public String artist;
    ...
}

And then you'd make your call and loop over the result:

Call<Map<String, Song>> call = ...
call.enqueue(new Callback<Map<String, Song>>() {

    @Override
    public void onResponse(Response<Map<String, Song>> response) {
        Map<String, Song> body = response.body();
        for (Song song : body.values()) {
            // your code here
        }
    }

    @Override
    public void onFailure(Throwable t) {
        // TODO
    }
});

You can even turn it into a list of songs if you need to for some reason:

List<Song> songs = new ArrayList<>(body.values());

Upvotes: 3

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