Question

I am developing an Android application and I need to retrieve the Google account used on the phone. I want to do this for the C2DM, but I don’t want to ask the user to enter in his/her Google email account if they are already logged in. Is there any way to do it?

Answer 1

Something like this should work:

AccountManager manager = (AccountManager) getSystemService(ACCOUNT_SERVICE);
Account[] list = manager.getAccounts();
String gmail = null;

for(Account account: list)
{
    if(account.type.equalsIgnoreCase("com.google"))
    {
        gmail = account.name;
        break;
    }
}

And you will need the following permission in your manifest:

<uses-permission android:name="android.permission.GET_ACCOUNTS"></uses-permission>

Remember to ‘Requesting Permissions at Run Time’ if you support Android 6 and later
https://developer.android.com/training/permissions/requesting.html

I wrote this from memory so it may need a little tweaking. Apparently it’s possible to register now without an email address, so maybe do some regexing on the data to ensure it’s actually an email address (ensure it contains @gmail or @googlemail)