The library is very easy to use, first make sure you have all the required jars in the classpath then have a look at the sample source bellow.
public void printContacts() { // Setup session and contact manager String username = "<gmail username or email address>"; String password = "<gmail password>"; GMSession session = new GMSession(username, password); GMContactManager manager = new GMContactManager(session); // Retrieve all contacts and do some processing on each contact GMContact[] contacts = manager.getAllGMContacts(); for (int i = 0; i < contacts.length; i++) { // Do some fancy stuff here } // Add a new contact GMContact contact = new GMContact( "TEST TESTINGSSON", "test.testingsson@testnet.com", "Test comment"); contact = manager.addGMContact(contact); // Update contact contact.setNote("A new note."); manager.updateGMContact(contact); // Remove contact. manager.removeGMContact(contact); // End session. manager = null; session.logout(); session = null; }