when to use retrofit and volley code example

Example 1: how to use retrofit in android

package info.androidhive.retrofit.rest;
 
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
 
 
public class ApiClient {
 
    public static final String BASE_URL = "http://api.themoviedb.org/3/";
    private static Retrofit retrofit = null;
 
 
    public static Retrofit getClient() {
        if (retrofit==null) {
            retrofit = new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
        }
        return retrofit;
    }
}

make a retrofit instance

Example 2: android retrofit2 example

compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.google.code.gson:gson:2.8.0'
compile 'com.squareup.retrofit2:converter-gson:2.1.0'