compile 'com.squareup.retrofit:retrofit:2.0.0-beta2'
compile 'com.squareup.retrofit:converter-gson:2.0.0-beta2'

public class User {
    @SerializedName("email")
    String email;

    @SerializedName("password")
    String password;

    public User(String email, String password) {
        this.email = email;
        this.password = password;
    }
}

public interface MyAPI {
    @GET("{roomID}")
    Call<List<Message>>loadMessages(@Path("roomID") String roomID);

    @POST("almabay_oauth/authorize")
    Call<User>login(@Body User user);
}

public class MainActivity extends AppCompatActivity {
String roomID = "548b737c0eadfb00eb93891bb28242e5";
MyAdapter adapter;
ListView lv;
List<Message> items;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    lv = (ListView) findViewById(R.id.lv);
    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("http://pms.vebific.com:81/chat/index/")
            .addConverterFactory(GsonConverterFactory.create())
            .build();

    MyAPI myAPI = retrofit.create(MyAPI.class);
    Call<List<Message>> call = myAPI.loadMessages(roomID);

    call.enqueue(new Callback<List<Message>>() {
        @Override
        public void onResponse(Response<List<Message>> response, Retrofit retrofit) {
            // Log.e("ResponseP", String.valueOf(response.body()));
            List<Message> items = response.body();
            Iterator iterator = items.iterator();
            while (iterator.hasNext()) {
                Message message = (Message) iterator.next();
                String user = message.getUser();
                //Log.e("User", user);
            }
            int statusCode = response.code();
            //Log.e("StatusCode", String.valueOf(statusCode));
            adapter = new MyAdapter(getApplicationContext(), items);
            lv.setAdapter(adapter);
        }

        @Override
        public void onFailure(Throwable t) {

        }
    });


    //--------------POST-------------

    Retrofit retrofit1 = new Retrofit.Builder()
            .baseUrl("http://phpstack-11819-25991-62288.cloudwaysapps.com/")
            .addConverterFactory(GsonConverterFactory.create())
            .build();
    MyAPI myPostApi = retrofit1.create(MyAPI.class);
    User user = new User("j@yahoo.com", "Admin123#");
    Call<User> call1 = myPostApi.login(user);
    call1.enqueue(new Callback<User>() {
        @Override
        public void onResponse(Response<User> response, Retrofit retrofit) {
            Log.e("Response code ", String.valueOf(response.code()));
            User user1 = response.body();
            Log.e("Response Message",response.message());
        }

        @Override
        public void onFailure(Throwable t) {

        }
    });
}