Basic Google Plus Sharing demonstrates the minimum code that is required to add sharing to Google+ from your app. You set up sharing by using the PlusShare.Builder methods, which you later build on to add advanced sharing features.
To add sharing:
Add a share button to your layout.
android:text="Share on Google+"
In your activity, configure your button’s OnClickListener to share when clicked.
When you share media to Google+, you cannot also use the setContentUrl method. If you want to include a URL in the post with the media, you should append the URL to the prefilled text in the setText() method.