Okhttp Interceptor issue

I'm trying to add a header to a simple okhttp (Get) request. How do I add the HttpHeader properly? Can I debug to ensure that my Header is actually sent to the server?

        Request request = new Request.Builder()
                .url("URL")
                .build();

        OkHttpClient okHttpClient = new OkHttpClient.Builder()
                .addInterceptor(new Interceptor() {
                    @Override
                    public okhttp3.Response intercept(Chain chain) throws IOException {
                        Request originalRequest = chain.request();
                        Request newRequest = originalRequest.newBuilder()
                                .addHeader("Header", "123")
                                .build();
                        return chain.proceed(newRequest);
                    }
                })
                .build();

        okHttpClient.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
             }

I've looked for basic simple examples but they are with Retrofit, GSON, Interfaces, or in Kotlin. Need to understand it codewise.

You can use by method addHeader send chain as param and add headers.

 Request getRequest = chain.request();
Request.Builder requestBuilder = getRequest.newBuilder()
.addHeader("Header", "123");
Request request = requestBuilder.build();
return chain.proceed(request);

You can also visit and look at the answers link1 and link2.

Here is the all-request Structure you can use.

OkHttpClient.Builder httpClient = new OkHttpClient.Builder();
httpClient.addInterceptor(new Interceptor() {
@Override
public Response intercept(Interceptor.Chain chain) throws IOException {
Request original = chain.request();
Request request = original.newBuilder()
.method(original.method(), original.body())
.build();
return chain.proceed(request);
}
};
OkHttpClient client = httpClient.build();
Request request = new Request.Builder()
.url("URL")
.addHeader("Header", "123")
.build();
client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
e.printStackTrace();
Log.d("OKHTTP3", e.getMessage());
// You get this failure
runOnUiThread(() -> {
});
}
@Override
public void onResponse(Call call, Response response) throws IOException {
try {
final String _body = response.body().string();
Log.d("OKHTTP3", _body);
runOnUiThread(() -> {
});
} catch (InterruptedIOException e) {
runOnUiThread(() -> {
// Or this exception depending when timeout is reached
});
}
}
});

Use addHeader() to add headers. header() sets the already added header name to the value.

Request newRequest = originalRequest.newBuilder()
.addHeader("Header", "123")
.build();

And to verify it's working correctly, you can use HttpLoggingInterceptor to log your network requests.

To check your request and to add headers, you can use interceptors.

To add headers, (copied from gist):

OkHttpClient.Builder httpClient = new OkHttpClient.Builder();  
httpClient.addInterceptor(new Interceptor() {  
@Override
public Response intercept(Interceptor.Chain chain) throws IOException {
Request original = chain.request();
Request request = original.newBuilder()
.header("User-Agent", "Your-App-Name")
.header("Accept", "application/vnd.yourapi.v1.full+json")
.method(original.method(), original.body())
.build();
return chain.proceed(request);
}
}
OkHttpClient client = httpClient.build();  
Retrofit retrofit = new Retrofit.Builder()  
.baseUrl(API_BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.client(client)
.build();

To see your headers, you can use sample example provided here:

class LoggingInterceptor implements Interceptor {
@Override public Response intercept(Interceptor.Chain chain) throws IOException {
Request request = chain.request();
long t1 = System.nanoTime();
logger.info(String.format("Sending request %s on %s%n%s",
request.url(), chain.connection(), request.headers()));
Response response = chain.proceed(request);
long t2 = System.nanoTime();
logger.info(String.format("Received response for %s in %.1fms%n%s",
response.request().url(), (t2 - t1) / 1e6d, response.headers()));
return response;
}
}