Android 9 (API level 28) introduces a number of changes to the Android system. The following behavior changes apply to all apps when they run on the Android 9 platform, regardless of the API level that they are targeting. All developers should review these changes and modify their apps to support them properly, where applicable to the app.
For changes that only affect apps that target API level 28 or higher, see Behavior changes: apps targeting API Level 28+.
Android 9 introduces new features to improve device power management. These changes, along with features that were already present before Android 9, help to ensure that system resources are made available to the apps that need them the most.
For details, see Power management.
To enhance user privacy, Android 9 introduces several behavior changes, such as limiting background apps' access to device sensors, restricting information retrieved from Wi-Fi scans, and new permission rules and permission groups related to phone calls, phone state, and Wi-Fi scans.
These changes affect all apps running on Android 9, regardless of target SDK version.
Limited access to sensors in background
Android 9 limits the ability for background apps to access user input and sensor data. If your app is running in the background on a device running Android 9, the system applies the following restrictions to your app:
- Your app cannot access the microphone or camera.
- Sensors that use the continuous reporting mode, such as accelerometers and gyroscopes, don't receive events.
- Sensors that use the on-change or one-shot reporting modes don't receive events.
If your app needs to detect sensor events on devices running Android 9, use a foreground service.
Restricted access to call logs
Android 9 introduces the
group and moves the
permissions into this group. In previous versions of Android, these permissions
were located in the
PHONE permission group.
CALL_LOG permission group gives users better control and visibility to
apps that need access to sensitive information about phone calls, such as
reading phone call records and identifying phone numbers.
Note: Because these permissions have changed groups and are granted at runtime, it's possible for the user to deny your app access to phone call logs information. In this case, your app should be able to handle the lack of access to information gracefully.
If your app is already following runtime permissions best practices, it can handle the change in permission group.
Restricted access to phone numbers
Apps running on Android 9 cannot read phone numbers or phone state without
first acquiring the
permission, in addition to the other permissions that your app's use cases
Phone numbers associated with incoming and outgoing calls are visible in the
such as for incoming and outgoing calls and are accessible from the
permission, however, the phone number field that's provided in
PHONE_STATE_CHANGED broadcasts and through
PhoneStateListener is empty.
To read phone numbers from phone state, update your app to request the necessary permissions based on your use case:
- To read numbers from the
PHONE_STATEintent action, you need both the
READ_CALL_LOGpermission and the
- To read numbers from
onCallStateChanged(), you need the
READ_CALL_LOGpermission only. You don't need the
Restricted access to Wi-Fi location and connection information
In Android 9, the permission requirements for an app to perform Wi-Fi scans are more strict than in previous versions. For details, see Wi-Fi scanning restrictions.
Similar restrictions also apply to the
method, which returns a
object describing the current Wi-Fi connection. You can only use this object's
methods to retrieve SSID and BSSID values if the calling app has the following
- ACCESS_FINE_LOCATION or ACCESS_COARSE_LOCATION
Retrieving the SSID or BSSID also requires location services to be enabled on the device (under Settings > Location).
Information removed from Wi-Fi service methods
In Android 9, the following events and broadcasts don't receive information about the user's location or personally identifiable data:
system broadcast from Wi-Fi no longer contains SSID (previously EXTRA_SSID),
BSSID (previously EXTRA_BSSID), or connection information (previously
EXTRA_NETWORK_INFO). If your app needs this information, call
Telephony information now relies on device location setting
If the user has disabled device location on a device running Android 9, the following methods don't provide results:
Restrictions on use of non-SDK interfaces
To help ensure app stability and compatibility, the platform restricts the use of some non-SDK methods and fields; these restrictions apply whether you attempt to access these methods and fields directly, via reflection, or using JNI. In Android 9, your app can continue to access these restricted interfaces; the platform uses toasts and log entries to bring them to your attention. If your app shows such a toast, it is important that you pursue an implementation strategy other than the restricted interface. If you feel that no alternative strategy is feasible, you may file a bug to request reconsideration of the restriction.
Restrictions on Non-SDK Interfaces contains further important information. You should review it to ensure that your app continues to function properly.
Security behavior changes
Device security changes
Android 9 adds several capabilities that improve your app's security, regardless of which version your app targets.
TLS implementation changes
The system's TLS implementation has undergone several changes in Android 9:
- If an instance of
SSLSocketfails to connect while it's being created, the system throws an
IOExceptioninstead of a
SSLEngineclass cleanly handles any
close_notifyalerts that occur.
To learn more about making secure web requests in an Android app, see An HTTPS example.
Stricter SECCOMP filter
Android 9 further restricts the system calls that are available to apps. This behavior is an extension of the SECCOMP filter that Android 8.0 (API level 26) includes.
Android 9 introduces several changes to the implementation and handling of cryptographic algorithms.
Conscrypt implementations of parameters and algorithms
Android 9 provides additional implementations of algorithm parameters in Conscrypt. These parameters include: AES, DESEDE, OAEP, and EC. The Bouncy Castle versions of these parameters and many algorithms have been deprecated as of Android 9.
If your app targets Android 8.1 (API level 27) or lower, you receive a warning
when requesting the Bouncy Castle implementation of one of these deprecated
algorithms. If you target Android 9, however, these requests each throw a
Android 9 introduces several other changes related to cryptography:
- When using PBE keys, if Bouncy Castle is expecting an initialization vector (IV) and your app doesn’t supply one, you receive a warning.
- The Conscrypt implementation of the ARC4 cipher allows you to specify either ARC4/ECB/NoPadding or ARC4/NONE/NoPadding.
- The Crypto Java Cryptography Architecture (JCA) provider has been removed. As
a result, if your app calls
SecureRandom.getInstance("SHA1PRNG", "Crypto"), a
- If your app parses RSA keys from buffers that are larger than the key structure, an exception no longer occurs.
To learn more about using Android's cryptographic capabilities, see Cryptography.
Android secure encrypted files are no longer supported
Android 9 completely removes support for Android secure encrypted files (ASECs).
In Android 2.2 (API level 8), Android introduced ASECs to support apps-on-SD-card functionality. On Android 6.0 (API level 23), the platform introduced an adoptable storage device technology that developers can use in place of ASECs.
Updates to the ICU libraries
Android 9 uses version 60 of the ICU library. Android 8.0 (API level 26) and Android 8.1 (API level 27) use ICU 58.
ICU is used to provide public APIs beneath the
and is used internally in the Android platform for internationalization support.
For example, it is used to implement Android classes in
The update to ICU 60 contains many small but useful changes, including Emoji 5.0 data support and improved date/time formats, as documented in the ICU 59 and ICU 60 release notes.
Notable changes in this update:
- The way the platform handles time zones has changed.
- The platform handles GMT and UTC better; UTC is no longer a synonym for
ICU now provides translated zone names for GMT and UTC. This change affects
android.icuformatting and parsing behavior for zones like "GMT", "Etc/GMT", "UTC", "Etc/UTC", and "Zulu".
java.text.SimpleDateFormatnow uses ICU to provide display names for UTC /GMT, meaning:
zzzzgenerates a long localized string for many locales. Previously, it produced "UTC" for UTC and strings like "GMT+00:00" for GMT.
zzzzrecognizes strings like "Universal Coordinated Time", and "Greenwich Mean Time".
- Apps may encounter compatibility problems if they assume
that "UTC" or "GMT+00:00" are output for
zzzzin all languages.
- The behavior of
- As with
SimpleDateFormat, UTC and GMT now have long names. DST variants of time zone names for the UTC zone, such as "UTC", "Etc/UTC", and "Zulu", become GMT+00:00, which is the standard fallback when there are no names available, rather than the hard-coded string
- Some zone IDs are correctly recognized as synonyms for other
zones, so that Android finds strings for
archaic zone IDs, such as
Eire, that previously could not be resolved.
- As with
- Asia/Hanoi is no longer a recognized zone. For this reason
java.util.TimeZones.getAvailableIds()does not return this value, and
java.util.TimeZone.getTimeZone()does not recognize it. This behavior is consistent with the existing
- The platform handles GMT and UTC better; UTC is no longer a synonym for GMT.
android.icu.text.NumberFormat.getInstance(ULocale, PLURALCURRENCYSTYLE).parse(String)method may throw a
ParseExceptioneven when parsing legitimate currency text. Avoid this problem by using
NumberFormat.parseCurrency, available since Android 7.0 (API level 24), for
PLURALCURRENCYSTYLE-style currency text.
Android Test changes
Android 9 introduces several changes to the Android Test framework's library and class structure. These changes help developers use framework-supported, public APIs, but the changes also allow for more flexibility in building and running tests using third-party libraries or custom logic.
Libraries removed from framework
Android 9 reorganizes the JUnit-based classes into three libraries:
android.test.base, android.test.runner, and android.test.mock.
This change allows you to run tests against a version of JUnit that works best
with your project's dependencies. This version of JUnit might be different than
the one that
To learn more about how the JUnit-based classes are organized into these libraries, as well as how to prepare your app's project for writing and running tests, see Set up project for Android Test.
Test suite build changes
addRequirements() method in the
class has been removed, and the
TestSuiteBuilder class itself been deprecated.
addRequirements() method had required developers to supply arguments whose
types are hidden APIs, making the API invalid.
Java UTF decoder
UTF-8 is the default charset in Android. A UTF-8 byte sequence can be decoded
String constructor, such as
The UTF-8 decoder in Android 9 follows the Unicode standards more strictly than in previous versions. The changes include the following:
- The non-shortest form of UTF-8, such as
<C0, AF>, is treated as ill-formed.
- The surrogate form of UTF-8, such as
U+DFFF, is treated as ill-formed.
- The maximal subpart is replaced by a single
U+FFFD. For example, in the byte sequence "
41 C0 AF 41 F4 80 80 41," the maximal subparts are "
AF," and "
F4 80 80." "
F4 80 80" can be the initial subsequence of "
F4 80 80 80", but "
C0" can't be the initial subsequence of any well-formed code unit sequence. Thus, the output should be "
- To decode a modified UTF-8 / CESU-8 sequence in Android 9 or higher, use the
DataInputStream.readUTF()method or the
Hostname verification using a certificate
RFC 2818 describes two
methods to match a domain name against a certificate—using the available
names within the
SAN) extension, or in the absence of a
SAN extension, falling back to the
However, the fallback to the
CN was deprecated in RFC 2818. For this reason,
Android no longer falls back to using the
CN. To verify a hostname, the server
must present a certificate with a matching
SAN. Certificates that don't
SAN matching the hostname are no longer trusted.
Network address lookups can cause network violations
Network address lookups that require name resolution can involve network I/O and are therefore considered blocking operations. Blocking operations on the main thread can cause pauses or jank.
StrictMode class is a development tool that helps
developers to detect problems in their code.
In Android 9 and higher,
StrictMode detects network
violations caused by network address lookups that require name resolution.
You should not ship your apps with
StrictMode enabled. If you do, then your
apps can experience exceptions, such as
NetworkOnMainThreadException when using the
detectAll() methods to get a
policy that detects network violations.
Resolving a numeric IP address isn't considered a blocking operation. Numeric IP address resolution works the same as in versions before Android 9.
In platform versions lower than Android 9, if a socket is
tagged using the
the socket is untagged when it's sent to another process using
In Android 9 and higher, the socket tag is kept when it’s sent to another
process using binder IPC. This change can affect network traffic statistics, for
example, when using the
If you want to retain the behavior of the previous versions, which untags a
socket that is sent to another process, you can call
untagSocket() before sending the
Reported amount of available bytes in socket
More detailed network capabilities reporting for VPNs
In Android 8.1 (API level 27) and lower, the
NetworkCapabilities class only reported a limited set of
information for VPNs, such as
TRANSPORT_VPN, but omitting
NET_CAPABILITY_NOT_VPN. This limited
information made it difficult to determine if using a VPN would result in charges
to the app's user. For example, checking
NET_CAPABILITY_NOT_METERED would not
determine whether the underlying networks were metered or not.
In Android 9 and higher, when a VPN calls the
method, the Android system merges the transports and capabilities of any
underlying networks and returns the result as the effective network capabilities
of the VPN network.
In Android 9 and higher, apps that already check for
NET_CAPABILITY_NOT_METERED receive the network capabilities of the VPN and the
Files in xt_qtaguid folder are no longer available to apps
Beginning with Android 9, apps are not allowed to have direct
read access to files in the
/proc/net/xt_qtaguid folder. The reason is to
ensure consistency with some devices that don't have these files at all.
The public APIs that rely on these files,
NetworkStatsManager, continue to work as intended.
However, the unsupported
functions, such as
may not work as expected—or at all— on different devices.
FLAG_ACTIVITY_NEW_TASK requirement is now enforced
With Android 9, you cannot start an activity from a
non-activity context unless you pass the intent flag
If you attempt to start an activity without passing this flag, the
activity does not start, and the system prints a message to the log.
Screen rotation changes
Beginning with Android 9, there are significant changes to the portrait rotation mode. In Android 8.0 (API level 26), users could toggle between auto-rotate and portrait rotation modes using a Quicksettings tile or Display settings. The portrait mode has been renamed rotation lock and it is active when auto-rotate is toggled off. There are no changes to auto-rotate mode.
When the device is in rotation lock mode, users can lock their screen to any
rotation supported by the top, visible Activity. An Activity should not assume
it will always be rendered in portrait. If the top Activity can be rendered in
multiple rotations in auto-rotate mode, the same options should be available in
rotation locked mode, with some exceptions based on the Activity's
screenOrientation setting (see the table below).
Activities that request a specific orientation (for example,
screenOrientation=landscape) ignore the user lock preference and behave
the same way as in Android 8.0.
The rotation lock mode works by setting the user rotation preference which the WindowManager uses when handling Activity rotation. The user rotation preference might be changed in the following cases. Note that there is a bias to return to the device's natural rotation, which is normally portrait for phone form factor devices:
- When the user accepts a rotation suggestion the rotation preference changes to the suggestion.
- When the user switches to a forced portrait app (including the lock screen or the launcher) the rotation preference changes to portrait.
The following table summarizes rotation behavior for the common screen orientations:
|In auto-rotate and rotation lock the Activity can be rendered in portrait or landscape (and the reverse). Expect to support both portrait and landscape layouts.
|In auto-rotate and rotation lock the Activity can be rendered in either landscape or reverse landscape. Expect to support only landscape layouts.
|In auto-rotate and rotation lock the Activity can be rendered in either portrait or reverse portrait. Expect to support only portrait layouts.
|In auto-rotate and rotation lock the Activity can be rendered in portrait or landscape (and the reverse). Expect to support both portrait and landscape layouts.
Rotation lock users will be given the option to lock to reverse portrait, often 180º.
|sensor, fullSensor, sensorPortrait, sensorLandscape
|The rotation lock mode preference is ignored and is treated as if auto-rotate is active. Only use this in exceptional circumstances with very careful UX consideration.
Apache HTTP client deprecation affects apps with non-standard ClassLoader
With Android 6.0,
we removed support for the Apache HTTP client.
This change has no effect on the great majority of apps that do not target
Android 9 or higher. However, the change can affect certain apps that
use a nonstandard
even if the apps do not target Android 9 or higher.
An app can be affected if it uses a non-standard
ClassLoader that explicitly
delegates to the system
ClassLoader. These apps need to delegate to the app
ClassLoader instead when looking for classes in
org.apache.http.*. If they
delegate to the system
ClassLoader, the apps will fail on Android 9 or higher
because those classes are no longer known to the system
prevent similar problems in the future, apps should in general load classes
through the app
ClassLoader rather than accessing the system
Apps running on Android 9 devices can discover every available camera by calling
An app should not assume that the device has only a single back camera or only a
single front camera.
For example, if your app has a button to switch between the front and back cameras, there may be more than one front or back camera to choose from. You should walk the camera list, examine each camera's characteristics, and decide which cameras to expose to the user.