OkHttpClient throws exception after upgrading to OkHttp3

Question

I'm using following lines of code to add a default header to all of my requests sent using Retrofit2:

private static OkHttpClient defaultHttpClient = new OkHttpClient();
static {
    defaultHttpClient.networkInterceptors().add(new Interceptor() {
        @Override
        public Response intercept(Chain chain) throws IOException {
            Request request = chain.request().newBuilder()
                    .addHeader("Accept", "Application/JSON").build();
            return chain.proceed(request);
        }
    });
}

After upgrading retrofit to beta-3 version, I had to upgrade OkHttp to OkHttp3 also (actually I just changed package names from okhttp to okhttp3, the library is included inside retrofit). After that I get exceptions from this line:

defaultHttpClient.networkInterceptors().add(new Interceptor());

Caused by: java.lang.UnsupportedOperationException at java.util.Collections$UnmodifiableCollection.add(Collections.java:932)

---

Caused by: java.lang.ExceptionInInitializerError

---

What is the problem here?

Answer 1

You have to use builder if you want to create OkHttp(3)Client object.

Try change this:

private static OkHttpClient defaultHttpClient = new OkHttpClient();

To something like this:

  OkHttpClient defaultHttpClient = new OkHttpClient.Builder()
       .addInterceptor(
           new Interceptor() {
             @Override
             public Response intercept(Interceptor.Chain chain) throws IOException {
                   Request request = chain.request().newBuilder()
                   .addHeader("Accept", "Application/JSON").build();
               return chain.proceed(request);
              }
           }).build();