java – How to handle a String in JSON format?

Question:

Let's say I receive the following content that is stored in a String:

{
    "client_id": 1580,
    "videos": 4,
    "remote_urls": [{
            "url": "rtsp://aniceurl.com"
        },
        {
            "url": "rtsp://aniceurl.com"
        },
        {
            "url": "rtsp://aniceurl.com"
        },
        {
            "url": "rtsp://aniceurl.com"
        }
    ],
    "action": "start"
}

I recognize the JSON and all, but it's saved in a String, not a JSONObject. I would like to know how I can extract the information from it and store it in variables/arrays, so I can work with this data.

[]'s!

Answer:

you can use google'sGson , it's super simple, just create a class that has exactly the same attributes as the json and parser it, look at the example I made with your json, just using the fromJson method fromJson(meuJson, MinhaClasse.class) :

CustomerDTO

import java.util.List;

public class ClienteDTO {
    private Integer client_id;
    private Integer videos;
    private List<RemoteUrlDTO> remote_urls;
    private String action;

    public Integer getClient_id() {
        return client_id;
    }
    public void setCliente_id(Integer cliente_id) {
        this.client_id = cliente_id;
    }
    public Integer getVideos() {
        return videos;
    }
    public void setVideos(Integer videos) {
        this.videos = videos;
    }
    public List<RemoteUrlDTO> getRemote_urls() {
        return remote_urls;
    }
    public void setRemote_urls(List<RemoteUrlDTO> remote_urls) {
        this.remote_urls = remote_urls;
    }
    public String getAction() {
        return action;
    }
    public void setAction(String action) {
        this.action = action;
    }
    @Override
    public String toString() {
        return "ClienteDTO [cliente_id=" + client_id + ", videos=" + videos + ", remote_urls=" + remote_urls
                + ", action=" + action + "]";
    }
}

RemoteUrlDTO

public class RemoteUrlDTO {
    private String url;

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    @Override
    public String toString() {
        return "RemoteUrlDTO [url=" + url + "]";
    }
}

Class for testing and demonstrating GSON:

import com.google.gson.Gson;

public class Main {
    public static void main(String[] args) {
        Gson g = new Gson();
        String json = "{\n" +
                "    \"client_id\": 1580,\n" +
                "    \"videos\": 4,\n" +
                "    \"remote_urls\": [{\n" +
                "            \"url\": \"rtsp://aniceurl.com\"\n" +
                "        },\n" +
                "        {\n" +
                "            \"url\": \"rtsp://aniceurl.com\"\n" +
                "        },\n" +
                "        {\n" +
                "            \"url\": \"rtsp://aniceurl.com\"\n" +
                "        },\n" +
                "        {\n" +
                "            \"url\": \"rtsp://aniceurl.com\"\n" +
                "        }\n" +
                "    ],\n" +
                "    \"action\": \"start\"\n" +
                "}\n" +
                "\n";


        ClienteDTO clienteDTO = g.fromJson(json, ClienteDTO.class);

        System.out.println(clienteDTO);
    }
}

Result after test execution

ClienteDTO [cliente_id=1580, videos=4, remote_urls=[RemoteUrlDTO [url=rtsp://aniceurl.com], RemoteUrlDTO [url=rtsp://aniceurl.com], RemoteUrlDTO [url=rtsp://aniceurl.com], RemoteUrlDTO [url=rtsp://aniceurl.com]], action=start]