AndroidDev- App取得google paly登錄的gmail帳號

想請問App內如何取得google play登錄的gmail帳號呢?

試過這個方法但無法取得, 在Android 8.0手機上運行，權限也有取得

AccountManager accountManager = AccountManager.get(context);
Account[] accounts = accountManager.getAccounts();
for(Account account : accounts){
Log.i('--Get Account Example--', account.name);
Log.i('--Get Account Example--', account.type);
}

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

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