I already have a sub class of Request<JSONObject> that is used for http post to the server. The problem is, I have no idea on how can I add a parameter for a file. Posting string to the server is easy. but I need to add file as a different parameter. How can I do it?
public class AddNewPetRequest extends Request<JSONObject> {
    private Response.Listener<JSONObject> listener;
    public AddNewPetRequest(String url, Map<String, String> params,
                                Response.Listener<JSONObject> reponseListener, Response.ErrorListener errorListener) {
        super(Request.Method.GET, url, errorListener);
        this.listener = reponseListener;
        this.params = params;
    }
    public AddNewPetRequest(int method, String url, Map<String, String> params,
                                Response.Listener<JSONObject> reponseListener, Response.ErrorListener errorListener) {
        super(method, url, errorListener);
        this.listener = reponseListener;
        this.params = params;
    }
    protected Map<String, String> getParams()
            throws com.android.volley.AuthFailureError {
        return params;
    };
    @Override
    protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
        try {
            String jsonString = new String(response.data,
                    HttpHeaderParser.parseCharset(response.headers));
            return Response.success(new JSONObject(jsonString),
                    HttpHeaderParser.parseCacheHeaders(response));
        } catch (UnsupportedEncodingException e) {
            return Response.error(new ParseError(e));
        } catch (JSONException je) {
            return Response.error(new ParseError(je));
        }
    }
    @Override
    protected void deliverResponse(JSONObject response) {
        // TODO Auto-generated method stub
        listener.onResponse(response);
    }
}
UPDATE QUESTION: I followed the pattern of one of the answers here in stackoverflow and I came up with this implementation:
public class MultipartRequest extends Request<String> {
private MultipartEntity entity = new MultipartEntity();
private final Response.Listener<String> mListener;
private HashMap<String, String> mParams;
public MultipartRequest(String url, Response.ErrorListener errorListener, Response.Listener<String> listener)
{
    super(Method.POST, url, errorListener);
    mListener = listener;
    buildMultipartEntity();
}
private void buildMultipartEntity()
{
    entity.addPart("profile_picture", new FileBody(new File("/storage/emulated/0/Pictures/VSCOCam/2015-07-31 11.55.14 1.jpg")));
    try
    {
        entity.addPart("user_id", new StringBody("15"));
        entity.addPart("name", new StringBody("Bogs"));
        entity.addPart("gender", new StringBody("Male"));
        entity.addPart("date_birth", new StringBody("1999-12-5"));
        entity.addPart("breed", new StringBody("monkey"));
    }
    catch (UnsupportedEncodingException e)
    {
        VolleyLog.e("UnsupportedEncodingException");
    }
}
@Override
public String getBodyContentType()
{
    return entity.getContentType().getValue();
}
@Override
public byte[] getBody() throws AuthFailureError
{
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    try
    {
        entity.writeTo(bos);
    }
    catch (IOException e)
    {
        VolleyLog.e("IOException writing to ByteArrayOutputStream");
    }
    return bos.toByteArray();
}
@Override
protected Response<String> parseNetworkResponse(NetworkResponse response)
{
    return Response.success("Uploaded", getCacheEntry());
}
@Override
protected void deliverResponse(String response)
{
    mListener.onResponse(response);
   
}
When I add this request to my request queue, it responded with a  com.android.volley.TimeoutError but if a check the data base, the request  executes and add items to the table but the profile picture upload has only 1 byte of size. another problem, my database item added twice.
 
     
    