Email adapter for AutoCompleteTextView that looks for emails from all account types, not just Google.

AllEmailAdapter.java

private static final String EMAIL_REGEX = "^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";
private static final Pattern EMAIL_PATTERN = Pattern.compile(EMAIL_REGEX);

private ArrayAdapter<String> getEmailAddressAdapter(Context context) {
    Account[] accounts = AccountManager.get(context).getAccounts();
    HashSet<String> emailSet = new HashSet<String>();
    for (int i = 0; i < accounts.length; i++) {
        if (isEmailAddress(accounts[i].name)) {
            emailSet.add(accounts[i].name);
        }
    }
    String[] emailArray = emailSet.toArray(new String[emailSet.size()]);
    return new ArrayAdapter<String>(context, android.R.layout.simple_dropdown_item_1line, emailArray);
}

private boolean isEmailAddress(String possibleEmail) {
    return EMAIL_PATTERN.matcher(possibleEmail).matches();
}

I recently discovered that Android already has an email regex built-in at android.util.Patterns#EMAIL_ADDRESS (though from Android 2.2+).

@orrc Neat. Had no idea that class existed.