Problems with Google Contacts Api in Java

I'm new to managing the Google Contacts app, I'm making a java desktop application to import contacts from Google, and create a project in OAuth 2.0, and I have all the credentials already, but I do not know where part of the code asks me for that data. I also have errors in 2 lines in the part of the code and I do not know what is due. Then I'll be leaving the code so you can have a look. Thanks in advance.

import com.google.gdata.client.*;
import com.google.gdata.client.contacts.*;
import com.google.gdata.data.*;
import com.google.gdata.data.contacts.*;
import com.google.gdata.data.extensions.*;
import com.google.gdata.util.*;
import java.io.IOException;
import java.net.URL;

public class prueba {


    public static void main(String[] args) {

        ContactsService myService = new ContactsService("YOUR_APPLICATION_NAME");
    }

    public static void printAllContacts(ContactsService myService)
    throws ServiceException, IOException {
  // Request the feed
  URL feedUrl = new URL("https://www.google.com/m8/feeds/contacts/default/full");
  ContactFeed resultFeed = myService.getFeed(feedUrl, ContactFeed.class);

  // Print the results
  System.out.println(resultFeed.getTitle().getPlainText());
  for (ContactEntry entry : resultFeed.getEntries()) {
    if (entry.hasName()) {
      Name name = entry.getName();
      if (name.hasFullName()) {
        String fullNameToDisplay = name.getFullName().getValue();
        if (name.getFullName().hasYomi()) {
          fullNameToDisplay += " (" + name.getFullName().getYomi() + ")";
        }
      System.out.println("\t\t" + fullNameToDisplay);
      } else {
        System.out.println("\t\t (no full name found)");
      }
      if (name.hasNamePrefix()) {
        System.out.println("\t\t" + name.getNamePrefix().getValue());
      } else {
        System.out.println("\t\t (no name prefix found)");
      }
      if (name.hasGivenName()) {
        String givenNameToDisplay = name.getGivenName().getValue();
        if (name.getGivenName().hasYomi()) {
          givenNameToDisplay += " (" + name.getGivenName().getYomi() + ")";
        }
        System.out.println("\t\t" + givenNameToDisplay);
      } else {
        System.out.println("\t\t (no given name found)");
      }
      if (name.hasAdditionalName()) {
        String additionalNameToDisplay = name.getAdditionalName().getValue();
        if (name.getAdditionalName().hasYomi()) {
          additionalNameToDisplay += " (" + name.getAdditionalName().getYomi() + ")";
        }
        System.out.println("\t\t" + additionalNameToDisplay);
      } else {
        System.out.println("\t\t (no additional name found)");
      }
      if (name.hasFamilyName()) {
        String familyNameToDisplay = name.getFamilyName().getValue();
        if (name.getFamilyName().hasYomi()) {
          familyNameToDisplay += " (" + name.getFamilyName().getYomi() + ")";
        }
        System.out.println("\t\t" + familyNameToDisplay);
      } else {
        System.out.println("\t\t (no family name found)");
      }
      if (name.hasNameSuffix()) {
        System.out.println("\t\t" + name.getNameSuffix().getValue());
      } else {
        System.out.println("\t\t (no name suffix found)");
      }
    } else {
      System.out.println("\t (no name found)");
    }
    System.out.println("Email addresses:");
    for (Email email : entry.getEmailAddresses()) {
      System.out.print(" " + email.getAddress());
      if (email.getRel() != null) {
        System.out.print(" rel:" + email.getRel());
      }
      if (email.getLabel() != null) {
        System.out.print(" label:" + email.getLabel());
      }
      if (email.getPrimary()) {
        System.out.print(" (primary) ");
      }
      System.out.print("\n");
    }
    System.out.println("IM addresses:");
    for (Im im : entry.getImAddresses()) {
      System.out.print(" " + im.getAddress());
      if (im.getLabel() != null) {
        System.out.print(" label:" + im.getLabel());
      }
      if (im.getRel() != null) {
        System.out.print(" rel:" + im.getRel());
      }
      if (im.getProtocol() != null) {
        System.out.print(" protocol:" + im.getProtocol());
      }
      if (im.getPrimary()) {
        System.out.print(" (primary) ");
      }
      System.out.print("\n");
    }
    System.out.println("Groups:");
    for (GroupMembershipInfo group : entry.getGroupMembershipInfos()) {
      String groupHref = group.getHref();
      System.out.println("  Id: " + groupHref);
    }
    System.out.println("Extended Properties:");
    for (ExtendedProperty property : entry.getExtendedProperties()) {
      if (property.getValue() != null) {
        System.out.println("  " + property.getName() + "(value) = " +
            property.getValue());
      } else if (property.getXmlBlob() != null) {
        System.out.println("  " + property.getName() + "(xmlBlob)= " +
            property.getXmlBlob().getBlob());
      }
    }
    Link photoLink = entry.getContactPhotoLink();
    String photoLinkHref = photoLink.getHref();
    System.out.println("Photo Link: " + photoLinkHref);
    if (photoLink.getEtag() != null) {
      System.out.println("Contact Photo's ETag: " + photoLink.getEtag());
    }
    System.out.println("Contact's ETag: " + entry.getEtag());
  }
}

}