Share cookies between WebView and OkHttpClient 3 / Retrofit 2. In the example I did the login on a web page in a WebView component and then I used the cookie to invoke a service from an activity

OtherActivity.java

//Setup the client
OkHttpClient client = new OkHttpClient.Builder()
        .cookieJar(new CookieJar() {

            @Override
            public void saveFromResponse(HttpUrl url, List<Cookie> cookies) {
            }

            @Override
            public List<Cookie> loadForRequest(HttpUrl url) {
                String cookie = getSharedPreferences(context).getString(Constants.COOKIE, "");
                return !cookie.isEmpty() ? Arrays.asList(Cookie.parse(url, cookie)) : Collections.EMPTY_LIST;
            }
        })
        .build();

//use the client with Retrofit
Retrofit retrofit = new Retrofit.Builder()
        .addConverterFactory(GsonConverterFactory.create())
        .client(client)
        .baseUrl(Constants.SERVER_URL)
        .build();

WebViewActivity.java

package com.nutcore.mementoparking;

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.webkit.CookieManager;
import android.webkit.CookieSyncManager;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

import java.util.HashMap;
import java.util.Map;

import okhttp3.Cookie;

import static com.nutcore.mementoparking.Constants.USERINFO;

public class WebViewActivity extends Activity {

    private WebView webView;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_social_side);

        webView = (WebView) findViewById(R.id.webView1);
        WebSettings settings = webView.getSettings();
        settings.setJavaScriptEnabled(true);
        settings.setBuiltInZoomControls(false);
        settings.setGeolocationEnabled(true);
        settings.setAppCacheEnabled(false);
        settings.setLoadsImagesAutomatically(true);
        webView.setWebViewClient(new WebViewClient());
        webView.loadUrl(Constants.SERVER_URL);
        webView.setWebViewClient(new WebViewClient() {

            public void onPageFinished(WebView view, String url) {
            //I save the cookies only when the user goes on login page
                if(url.equals(Constants.LOGIN_URL)){
                    CookieSyncManager syncManager = CookieSyncManager.createInstance(webView.getContext());
                    CookieManager cookieManager = CookieManager.getInstance();

                    String cookie = cookieManager.getCookie(url);
                    SharedPreferences.Editor editor = getEditor(SocialSideActivity.this);
                    editor.putString(Constants.COOKIE, cookie);
                    editor.commit();
                    syncManager.sync();
                }
            }
        });

    }

    private SharedPreferences.Editor getEditor(Context context) {
        SharedPreferences settings = getSharedPreferences(context);
        return settings.edit();
    }

    private SharedPreferences getSharedPreferences(Context context) {
        return context.getSharedPreferences(USERINFO, 0);
    }


}