ANDROID_ID の Android 8.0 における仕様変更
ANDROID_ID が Android 8.0(Oreo: API-26)において仕様変更されたようだ。このため、従来のように ANDROID_ID がデバイス固有の ID と思って扱っていると、意図しない結果につながる。 Android ID In O, Android ID (Settings.Secure.ANDROID_ID or SSAID) has a different value for each app and each user on the device. Developers requiring a device-scoped identifier, should instead use a resettable identifier, such as Advertising ID, giving users more control. Advertising ID also provides a user-facing setting to limit ad tracking. Additionally in Android O: The ANDROID_ID value won't change on package uninstall/reinstall, as long as the package name and signing key are the same. Apps can rely on this value to maintain state across reinstalls. If an app was installed on a device running an earlier version of Android, the Android ID remains the same when the device is updated to Android O, unless the app is uninstalled and reinstalled. The Android ID value only changes if the device is factory reset or if the signing key rotates between uninstall and