CODEWITHSUNDEEP
javaandroidjsonpostgson
David Velasquez
David Velasquez

Reputation: 2366

Serialize ArrayList of custom class to JSON using Gson and send data over HTTP

I would like to convert the data in an ArrayList to JSON and then send it to my webserver. The list mTeamDataList is of type ArrayList<TeamData>.

The TeamData class is:

public class TeamData
{
    String mFullName;
    String mShortName;
    String mLeague;

    //constructor, getters and setters are here
}

I have a addTeamsToDB() method that is responsible for writing the data in the array to the webserver. Here is what I have so far:

public static void addTeamsToDB()
{
    if(mTeamDataList.size() == 0)
        return;

    HttpURLConnection urlConnection = null;
    String addTeamURL = "http://api.somewebsite.com/add_team.php";

    try
    {
        Gson gson = new Gson();
        URL urlObj = new URL(addTeamURL);
        urlConnection = (HttpURLConnection) urlObj.openConnection();
        urlConnection.setDoOutput(true);
        urlConnection.setRequestMethod("POST");
        urlConnection.connect();

        //I believe converting to json goes here

        OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream());

    } 
    catch (IOException e)
    {
        e.printStackTrace();
    }
    finally
    {
        assert urlConnection != null;
        urlConnection.disconnect();
    }
}

I found several answers on SO but they only showed basic examples of inserting one object or hard-coded data. I have not found one to convert an array of custom data-type objects to JSON using Gson.

Is there a method that does this or do I have to manually convert each item in the array through a loop?

I was following this tutorial but he's using the NameValuePairs class to achieve this. But it's deprecated so I'm not sure what to use instead.

Also, the tutorial is using the built-in JSON java library so if someone can show the Gson way instead, that would be very helpful.

Upvotes: 0

Views: 9102

Answers (2)

Vic Seedoubleyew
Vic Seedoubleyew

Reputation: 10556

If your class has nothing more than what you posted, then there shouldn't be a problem using Gson's toJson(Object src, Type typeOfSrc) directly on your ArrayList :

Type listType = new TypeToken<ArrayList<TeamData>>() {}.getType();
String json = gson.toJson(mTeamDataList, listType);

The reason for that, is that your TeamData class has only generic fields.

Of course, if you want the "keys" to appear in your JSON, you should add the @SerializedName annotation on your class members.

Then, to send the data using your HttpUrlConnection, replace the line where you declare your out variable by :

OutputStreamWriter wr= new OutputStreamWriter(urlConnection.getOutputStream());
wr.write(json);

Upvotes: 7

Krish
Krish

Reputation: 3885

Use the class some think like this,

import com.google.gson.annotations.SerializedName;

import java.util.ArrayList;

/**
 * @author Krish
 */
public class TeamDataList {

    @SerializedName("mTeamDataList")
    private ArrayList<TeamData> mTeamDataList;

    public TeamDataList(ArrayList<TeamData> teamDataList) {
        this.mTeamDataList = teamDataList;
    }

    public class TeamData {
        @SerializedName("mFullName")
        String mFullName;
        @SerializedName("mShortName")
        String mShortName;
        @SerializedName("mLeague")
        String mLeague;

        //constructor, getters and setters are here
    }

}

And use this this method for serializing,

public static String toJson(Object object) {
        Gson gson = new Gson();
        return gson.toJson(object);
    }

Upvotes: 1

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