行為變更：指定 Android 15 以上版本的應用程式

透過集合功能整理內容 你可以依據偏好儲存及分類內容。

和先前版本一樣，Android 15 也包含可能會影響應用程式的行為變更。以下行為變更僅適用於指定 Android 15 以上版本的應用程式。如果應用程式指定 Android 15 以上版本，則應修改應用程式，以便在適用情況下正確支援這些行為。

無論應用程式的 targetSdkVersion 為何，也請務必查看影響所有在 Android 15 上執行的應用程式行為變更清單。

核心功能

Android 15 會修改或擴充 Android 系統的各種核心功能。

前景服務異動

We are making the following changes to foreground services with Android 15.

• Data sync foreground service timeout behavior
• New media processing foreground service type
• Restrictions on BOOT_COMPLETED broadcast receivers launching foreground services
• Restrictions on starting foreground services while an app holds the SYSTEM_ALERT_WINDOW permission

Data sync foreground service timeout behavior

Android 15 為指定 Android 15 (API 級別 35) 以上版本為目標版本的應用程式，在 dataSync 中導入新的逾時行為。這項行為也適用於新的mediaProcessing前景服務類型。

系統允許應用程式的 dataSync 服務在 24 小時內執行總共 6 小時，之後系統會呼叫執行中的服務 Service.onTimeout(int, int) 方法 (在 Android 15 中推出)。此時，服務有幾秒的時間可以呼叫 Service.stopSelf()。呼叫 Service.onTimeout() 後，系統就不會再將服務視為前景服務。如果服務未呼叫 Service.stopSelf()，系統會擲回內部例外狀況。例外狀況會記錄在 Logcat 中，並顯示以下訊息：

Fatal Exception: android.app.RemoteServiceException: "A foreground service of
type dataSync did not stop within its timeout: [component name]"

如要避免這項行為變更帶來的問題，您可以執行下列一或多項操作：

1. 讓您的服務實作新的 Service.onTimeout(int, int) 方法。應用程式收到回呼時，請務必在幾秒內呼叫 stopSelf()。(如果您沒有立即停止應用程式，系統會產生失敗)。
2. 確認應用程式的 dataSync 服務在任何 24 小時內的執行時間不超過 6 小時 (除非使用者與應用程式互動，並重設計時器)。
3. 只有在使用者直接互動時，才啟動 dataSync 前景服務；由於服務啟動時應用程式處於前景，因此服務在應用程式進入背景後，可執行完整的六小時。
4. 請改用其他 API，而非 dataSync 前景服務。

如果應用程式的 dataSync 前景服務在過去 24 小時內已執行 6 小時，則「除非」使用者將應用程式移至前景 (會重設計時器)，否則您無法啟動另一項 dataSync 前景服務。如果您嘗試啟動另一項 dataSync 前景服務，系統會擲回 ForegroundServiceStartNotAllowedException，並顯示錯誤訊息「Time limit is Of for 前景服務類型 dataSync」

測試

如要測試應用程式的行為，您可以啟用資料同步處理逾時，即使應用程式並非以 Android 15 為目標版本 (只要應用程式是在 Android 15 裝置上執行)，也能啟用。如要啟用逾時值，請執行下列 adb 指令：

adb shell am compat enable FGS_INTRODUCE_TIME_LIMITS your-package-name

您也可以調整逾時期限，方便測試應用程式在達到限制時的行為。如要設定新的逾時期限，請執行下列 adb 指令：

adb shell device_config put activity_manager data_sync_fgs_timeout_duration duration-in-milliseconds

New media processing foreground service type

Android 15 introduces a new foreground service type, mediaProcessing. This service type is appropriate for operations like transcoding media files. For example, a media app might download an audio file and need to convert it to a different format before playing it. You can use a mediaProcessing foreground service to make sure the conversion continues even while the app is in the background.

The system permits an app's mediaProcessing services to run for a total of 6 hours in a 24-hour period, after which the system calls the running service's Service.onTimeout(int, int) method (introduced in Android 15). At this time, the service has a few seconds to call Service.stopSelf(). If the service does not call Service.stopSelf(), the system throws an internal exception. The exception is logged in Logcat with the following message:

Fatal Exception: android.app.RemoteServiceException: "A foreground service of
type mediaProcessing did not stop within its timeout: [component name]"

To avoid having the exception, you can do one of the following:

1. Have your service implement the new Service.onTimeout(int, int) method. When your app receives the callback, make sure to call stopSelf() within a few seconds. (If you don't stop the app right away, the system generates a failure.)
2. Make sure your app's mediaProcessing services don't run for more than a total of 6 hours in any 24-hour period (unless the user interacts with the app, resetting the timer).
3. Only start mediaProcessing foreground services as a result of direct user interaction; since your app is in the foreground when the service starts, your service has the full six hours after the app goes to the background.
4. Instead of using a mediaProcessing foreground service, use an alternative API, like WorkManager.

If your app's mediaProcessing foreground services have run for 6 hours in the last 24, you cannot start another mediaProcessing foreground service unless the user has brought your app to the foreground (which resets the timer). If you try to start another mediaProcessing foreground service, the system throws ForegroundServiceStartNotAllowedException with an error message like "Time limit already exhausted for foreground service type mediaProcessing".

For more information about the mediaProcessing service type, see Changes to foreground service types for Android 15: Media processing.

Testing

To test your app's behavior, you can enable media processing timeouts even if your app is not targeting Android 15 (as long as the app is running on an Android 15 device). To enable timeouts, run the following adb command:

adb shell am compat enable FGS_INTRODUCE_TIME_LIMITS your-package-name

You can also adjust the timeout period, to make it easier to test how your app behaves when the limit is reached. To set a new timeout period, run the following adb command:

adb shell device_config put activity_manager media_processing_fgs_timeout_duration duration-in-milliseconds

Restrictions on BOOT_COMPLETED broadcast receivers launching foreground services

There are new restrictions on BOOT_COMPLETED broadcast receivers launching foreground services. BOOT_COMPLETED receivers are not allowed to launch the following types of foreground services:

• dataSync
• camera
• mediaPlayback
• phoneCall
• mediaProjection
• microphone (this restriction has been in place for microphone since Android 14)

If a BOOT_COMPLETED receiver tries to launch any of those types of foreground services, the system throws ForegroundServiceStartNotAllowedException.

Testing

To test your app's behavior, you can enable these new restrictions even if your app is not targeting Android 15 (as long as the app is running on an Android 15 device). Run the following adb command:

adb shell am compat enable FGS_BOOT_COMPLETED_RESTRICTIONS your-package-name

To send a BOOT_COMPLETED broadcast without restarting the device, run the following adb command:

adb shell am broadcast -a android.intent.action.BOOT_COMPLETED your-package-name

Restrictions on starting foreground services while an app holds the SYSTEM_ALERT_WINDOW permission

先前，如果應用程式擁有 SYSTEM_ALERT_WINDOW 權限，即使目前處於背景執行狀態，也能啟動前景服務 (如「背景啟動限制的例外狀況」一文所述)。

如果應用程式指定 Android 15 為目標版本，這項豁免權現在比較縮小。應用程式現在需要具備 SYSTEM_ALERT_WINDOW 權限，且也設有可見的重疊視窗。也就是說，應用程式必須先啟動 TYPE_APPLICATION_OVERLAY 視窗，「而且」必須先顯示該視窗，才能啟動前景服務。

如果應用程式嘗試從背景啟動前景服務，但不符合這些新要求 (且沒有其他例外狀況)，系統會擲回 ForegroundServiceStartNotAllowedException。

如果您的應用程式聲明 SYSTEM_ALERT_WINDOW 權限，並從背景啟動前景服務，可能會受到這項變更的影響。如果應用程式收到 ForegroundServiceStartNotAllowedException，請檢查應用程式的運算順序，並確認應用程式在嘗試從背景啟動前景服務前，已擁有有效的疊加式視窗。您可以呼叫 View.getWindowVisibility()，檢查覆疊視窗目前是否可見，也可以覆寫 View.onWindowVisibilityChanged()，在可見度變更時收到通知。

測試

如要測試應用程式的行為，您可以啟用這些新限制，即使應用程式並非以 Android 15 為目標版本 (只要應用程式在 Android 15 裝置上執行) 也一樣。如要啟用這些新限制，以便從背景啟動前景服務，請執行下列 adb 指令：

adb shell am compat enable FGS_SAW_RESTRICTIONS your-package-name

變更應用程式可修改「零打擾」模式全域狀態的時機

Apps that target Android 15 (API level 35) and higher can no longer change the global state or policy of Do Not Disturb (DND) on a device (either by modifying user settings, or turning off DND mode). Instead, apps must contribute an AutomaticZenRule, which the system combines into a global policy with the existing most-restrictive-policy-wins scheme. Calls to existing APIs that previously affected global state (setInterruptionFilter, setNotificationPolicy) result in the creation or update of an implicit AutomaticZenRule, which is toggled on and off depending on the call-cycle of those API calls.

Note that this change only affects observable behavior if the app is calling setInterruptionFilter(INTERRUPTION_FILTER_ALL) and expects that call to deactivate an AutomaticZenRule that was previously activated by their owners.

OpenJDK API 異動

Android 15 持續更新 Android 核心程式庫，以便與最新版 OpenJDK LTS 中的功能保持一致。

以下部分變更可能會影響以 Android 15 (API 級別 35) 為目標版本的應用程式相容性：

• 字串格式 API 異動：使用下列 String.format() 和 Formatter.format() API 時，對引數索引、標記、寬度和精確度的驗證會更加嚴格：

  • String.format(String, Object[])
  • String.format(Locale, String, Object[])
  • Formatter.format(String, Object[])
  • Formatter.format(Locale, String, Object[])

  舉例來說，如果使用 0 的引數索引 (格式字串中的 %0)，系統會擲回下列例外狀況：

  IllegalFormatArgumentIndexException: Illegal format argument index = 0
  

  在這種情況下，您可以使用引數索引 1 (格式字串中的 %1) 來修正問題。

• 變更 Arrays.asList(...).toArray() 的元件類型：使用 Arrays.asList(...).toArray() 時，產生的陣列元件類型現在是 Object，而不是基礎陣列元素的類型。因此，以下程式碼會擲回 ClassCastException：

  String[] elements = (String[]) Arrays.asList("one", "two").toArray();
  

  在這種情況下，如要將 String 保留為結果陣列中的元件類型，您可以改用 Collection.toArray(Object[])：

  String[] elements = Arrays.asList("two", "one").toArray(new String[0]);
  

• 語言代碼處理方式異動：使用 Locale API 時，希伯來文、意第緒文和印尼文的語言代碼將不再轉換為舊版 (希伯來文：iw、意第緒文：ji、印尼文：in)。指定這些語言代碼時，請改用 ISO 639-1 的代碼 (希伯來文：he、意第緒文：yi、印尼文：id)。

• 隨機整數序列的變更：根據 https://bugs.openjdk.org/browse/JDK-8301574 所做的變更，下列 Random.ints() 方法現在會傳回與 Random.nextInt() 方法不同的數字序列：

  • Random.ints(long)
  • Random.ints(long, int, int)
  • Random.ints(int, int)
  • Random.ints()

  一般來說，這項變更不應導致應用程式中斷行為，但程式碼不應預期從 Random.ints() 方法產生的序列會與 Random.nextInt() 相符。

在應用程式的建構設定中更新 compileSdk 以使用 Android 15 (API 級別 35)後，新的 SequencedCollection API 可能會影響應用程式的相容性：

• 與 kotlin-stdlib 中的 MutableList.removeFirst() 和 MutableList.removeLast() 擴充函式發生衝突

  Java 中的 List 類型會對應至 Kotlin 中的 MutableList 類型。由於 List.removeFirst() 和 List.removeLast() API 已在 Android 15 (API 級別 35) 中推出，因此 Kotlin 編譯器會將函式呼叫 (例如 list.removeFirst()) 靜態解析為新的 List API，而非 kotlin-stdlib 中的擴充功能函式。

  如果應用程式重新編譯時，compileSdk 設為 35，minSdk 設為 34 或更低版本，然後在 Android 14 以下版本上執行應用程式，系統就會擲回執行階段錯誤：

  java.lang.NoSuchMethodError: No virtual method
  removeFirst()Ljava/lang/Object; in class Ljava/util/ArrayList;
  

  Android Gradle 外掛程式中現有的 NewApi lint 選項可以擷取這些新的 API 用法。

  ./gradlew lint
  
  MainActivity.kt:41: Error: Call requires API level 35 (current min is 34): java.util.List#removeFirst [NewApi]
        list.removeFirst()
  

  如要修正這個例外狀況和 Lint 錯誤，請在 Kotlin 中將 removeFirst() 和 removeLast() 函式呼叫分別替換為 removeAt(0) 和 removeAt(list.lastIndex)。如果您使用的是 Android Studio Ladybug | 2024.1.3 以上版本，則可針對這些錯誤使用快速修正選項。

  如果已停用 Lint 選項，建議您移除 @SuppressLint("NewApi") 和 lintOptions { disable 'NewApi' }。

• 與 Java 中的其他方法衝突

  我們已在現有類型中新增新方法，例如 List 和 Deque。這些新方法可能與其他介面和類別中具有相同名稱和引數類型的其他方法不相容。如果方法簽章與不相容性發生衝突，javac 編譯器會輸出建構時間錯誤。例如：

  錯誤示例 1：

  javac MyList.java
  
  MyList.java:135: error: removeLast() in MyList cannot implement removeLast() in List
    public void removeLast() {
                ^
    return type void is not compatible with Object
    where E is a type-variable:
      E extends Object declared in interface List
  

  錯誤示例 2：

  javac MyList.java
  
  MyList.java:7: error: types Deque<Object> and List<Object> are incompatible;
  public class MyList implements  List<Object>, Deque<Object> {
    both define reversed(), but with unrelated return types
  1 error
  

  錯誤示例 3：

  javac MyList.java
  
  MyList.java:43: error: types List<E#1> and MyInterface<E#2> are incompatible;
  public static class MyList implements List<Object>, MyInterface<Object> {
    class MyList inherits unrelated defaults for getFirst() from types List and MyInterface
    where E#1,E#2 are type-variables:
      E#1 extends Object declared in interface List
      E#2 extends Object declared in interface MyInterface
  1 error
  

  如要修正這些建構錯誤，實作這些介面的類別應覆寫方法，並使用相容的傳回類型。例如：

  @Override
  public Object getFirst() {
      return List.super.getFirst();
  }
  

安全性

Android 15 包含提升系統安全性的變更，可協助保護應用程式和使用者免受惡意應用程式的侵害。

受限 TLS 版本

Android 15 restricts the usage of TLS versions 1.0 and 1.1. These versions had previously been deprecated in Android, but are now disallowed for apps targeting Android 15.

安全的背景活動啟動

Android 15 可保護使用者不受惡意應用程式侵擾，並讓使用者進一步控管 方法是加入可防止惡意背景應用程式的變更 將其他應用程式移至前景、提升其權限並濫用 互動。自以下日期起，系統已限制啟動背景活動： Android 10 (API 級別 29)。

禁止與堆疊頂端 UID 不符的應用程式啟動活動

惡意應用程式可能會在同一工作中啟動其他應用程式的活動，然後 疊加在上，營造出該應用程式的錯覺這項「工作」 駭客」攻擊會避開目前的背景啟動限制，因為這 發生在相同的可見工作中為降低這種風險，Android 15 新增了 旗標，防止應用程式啟動與堆疊上頂層 UID 不符的應用程式 活動。如要選擇加入應用程式的所有活動，請更新 allowCrossUidActivitySwitchFromBelow敬上 屬性加入應用程式的 AndroidManifest.xml 檔案中：

<application android:allowCrossUidActivitySwitchFromBelow="false" >

如果符合下列所有條件，系統就會啟用新的安全措施：

• 執行啟動作業的應用程式以 Android 15 為目標。
• 工作堆疊頂端的應用程式以 Android 15 為目標。
• 所有可見的活動已選擇採用新的保護措施

啟用安全措施後，應用程式可能會返回主畫面，而非 則最後顯示的應用程式。

其他變更

除了 UID 比對的限制外，下列其他變更也會 包含：

• 變更 PendingIntent 位創作者，禁止開啟背景活動，包括： default。這可避免應用程式意外 PendingIntent，可能遭不肖人士濫用。
• 除非 PendingIntent 傳送者，否則請勿將應用程式移至前景 這項異動旨在避免惡意應用程式濫用 可在背景啟動活動根據預設，應用程式 允許將工作堆疊移至前景，除非創作者允許 背景活動啟動權限或傳送者有背景活動 啟動權限。
• 控管工作堆疊的主要活動如何完成任務。如果 完成一項任務後，Android 就會回到 上次使用時間。此外，如果非頂層活動完成任務，Android 就會 返回主畫面。也不會阻斷 活動。
• 避免從其他應用程式啟動任意活動 工作。這項變更藉由建立 假冒其他應用程式的活動。
• 禁止將不可見的視窗視為背景活動 產品發布。避免惡意應用程式濫用背景 使用者啟動活動後，系統會顯示擾人或惡意的內容。

更安全的意圖

Android 15 introduces new optional security measures to make intents safer and more robust. These changes are aimed at preventing potential vulnerabilities and misuse of intents that can be exploited by malicious apps. There are two main improvements to the security of intents in Android 15:

• Match target intent-filters: Intents that target specific components must accurately match the target's intent-filter specifications. If you send an intent to launch another app's activity, the target intent component needs to align with the receiving activity's declared intent-filters.
• Intents must have actions: Intents without an action will no longer match any intent-filters. This means that intents used to start activities or services must have a clearly defined action.

In order to check how your app responds to these changes, use StrictMode in your app. To see detailed logs about Intent usage violations, add the following method:

fun onCreate() {
    StrictMode.setVmPolicy(VmPolicy.Builder()
        .detectUnsafeIntentLaunch()
        .build()
    )
}

public void onCreate() {
    StrictMode.setVmPolicy(new VmPolicy.Builder()
            .detectUnsafeIntentLaunch()
            .build());
}

使用者體驗和系統使用者介面

Android 15 包含一些變更，旨在打造更一致、直覺的使用者體驗。

視窗插邊變更

Android 15 有兩項與視窗內嵌相關的變更：預設會強制執行邊到邊，且有設定變更，例如系統列的預設設定。

Edge-to-edge enforcement

Apps are edge-to-edge by default on devices running Android 15 if the app is targeting Android 15 (API level 35).

This is a breaking change that might negatively impact your app's UI. The changes affect the following UI areas:

• Gesture handle navigation bar
  • Transparent by default.
  • Bottom offset is disabled so content draws behind the system navigation bar unless insets are applied.
  • setNavigationBarColor and R.attr#navigationBarColor are deprecated and don't affect gesture navigation.
  • setNavigationBarContrastEnforced and R.attr#navigationBarContrastEnforced continue to have no effect on gesture navigation.
• 3-button navigation
  • Opacity set to 80% by default, with color possibly matching the window background.
  • Bottom offset disabled so content draws behind the system navigation bar unless insets are applied.
  • setNavigationBarColor and R.attr#navigationBarColor are set to match the window background by default. The window background must be a color drawable for this default to apply. This API is deprecated but continues to affect 3-button navigation.
  • setNavigationBarContrastEnforced and R.attr#navigationBarContrastEnforced is true by default, which adds an 80% opaque background across 3-button navigation.
• Status bar
  • Transparent by default.
  • The top offset is disabled so content draws behind the status bar unless insets are applied.
  • setStatusBarColor and R.attr#statusBarColor are deprecated and have no effect on Android 15.
  • setStatusBarContrastEnforced and R.attr#statusBarContrastEnforced are deprecated but still have an effect on Android 15.
• Display cutout
  • layoutInDisplayCutoutMode of non-floating windows must be LAYOUT_IN_DISPLAY_CUTOUT_MODE_ALWAYS. SHORT_EDGES, NEVER, and DEFAULT are interpreted as ALWAYS so that users don't see a black bar caused by the display cutout and appear edge-to-edge.

The following example shows an app before and after targeting Android 15 (API level 35), and before and after applying insets.

What to check if your app is already edge-to-edge

If your app is already edge-to-edge and applies insets, you are mostly unimpacted, except in the following scenarios. However, even if you think you aren't impacted, we recommend you test your app.

• You have a non-floating window, such as an Activity that uses SHORT_EDGES, NEVER or DEFAULT instead of LAYOUT_IN_DISPLAY_CUTOUT_MODE_ALWAYS. If your app crashes on launch, this might be due to your splashscreen. You can either upgrade the core splashscreen dependency to 1.2.0-alpha01 or later or set window.attributes.layoutInDisplayCutoutMode = WindowManager.LayoutInDisplayCutoutMode.always.
• There might be lower-traffic screens with occluded UI. Verify these less-visited screens don't have occluded UI. Lower-traffic screens include:
  • Onboarding or sign-in screens
  • Settings pages

What to check if your app is not already edge-to-edge

If your app is not already edge-to-edge, you are most likely impacted. In addition to the scenarios for apps that are already edge-to-edge, you should consider the following:

• If your app uses Material 3 Components ( androidx.compose.material3) in compose, such as TopAppBar, BottomAppBar, and NavigationBar, these components are likely not impacted because they automatically handle insets.
• If your app is using Material 2 Components ( androidx.compose.material) in Compose, these components don't automatically handle insets. However, you can get access to the insets and apply them manually. In androidx.compose.material 1.6.0 and later, use the windowInsets parameter to apply the insets manually for BottomAppBar, TopAppBar, BottomNavigation, and NavigationRail. Likewise, use the contentWindowInsets parameter for Scaffold.
• If your app uses views and Material Components (com.google.android.material), most views-based Material Components such as BottomNavigationView, BottomAppBar, NavigationRailView, or NavigationView, handle insets and require no additional work. However, you need to add android:fitsSystemWindows="true" if using AppBarLayout.
• For custom composables, apply the insets manually as padding. If your content is within a Scaffold, you can consume insets using the Scaffold padding values. Otherwise, apply padding using one of the WindowInsets.
• If your app is using views and BottomSheet, SideSheet or custom containers, apply padding using ViewCompat.setOnApplyWindowInsetsListener. For RecyclerView, apply padding using this listener and also add clipToPadding="false".

What to check if your app must offer custom background protection

If your app must offer custom background protection to 3-button navigation or the status bar, your app should place a composable or view behind the system bar using WindowInsets.Type#tappableElement() to get the 3-button navigation bar height or WindowInsets.Type#statusBars.

Additional edge-to-edge resources

See the Edge to Edge Views and Edge to Edge Compose guides for additional considerations on applying insets.

Deprecated APIs

The following APIs are deprecated but not disabled:

• R.attr#enforceStatusBarContrast
• R.attr#navigationBarColor (for 3 button navigation, with 80% alpha)
• Window#isStatusBarContrastEnforced
• Window#setNavigationBarColor (for 3 button navigation, with 80% alpha)
• Window#setStatusBarContrastEnforced

The following APIs are deprecated and disabled:

• R.attr#navigationBarColor (for gesture navigation)
• R.attr#navigationBarDividerColor
• R.attr#statusBarColor
• Window#setDecorFitsSystemWindows
• Window#getNavigationBarColor
• Window#getNavigationBarDividerColor
• Window#getStatusBarColor
• Window#setNavigationBarColor (for gesture navigation)
• Window#setNavigationBarDividerColor
• Window#setStatusBarColor

Stable configuration

If your app targets Android 15 (API level 35) or higher, Configuration no longer excludes the system bars. If you use the screen size in the Configuration class for layout calculation, you should replace it with better alternatives like an appropriate ViewGroup, WindowInsets, or WindowMetricsCalculator depending on your need.

Configuration has been available since API 1. It is typically obtained from Activity.onConfigurationChanged. It provides information like window density, orientation, and sizes. One important characteristic about the window sizes returned from Configuration is that it previously excluded the system bars.

The configuration size is typically used for resource selection, such as /res/layout-h500dp, and this is still a valid use case. However, using it for layout calculation has always been discouraged. If you do so, you should move away from it now. You should replace the use of Configuration with something more suitable depending on your use case.

If you use it to calculate the layout, use an appropriate ViewGroup, such as CoordinatorLayout or ConstraintLayout. If you use it to determine the height of the system navbar, use WindowInsets. If you want to know the current size of your app window, use computeCurrentWindowMetrics.

The following list describes the fields affected by this change:

• Configuration.screenWidthDp and screenHeightDp sizes no longer exclude the system bars.
• Configuration.smallestScreenWidthDp is indirectly affected by changes to screenWidthDp and screenHeightDp.
• Configuration.orientation is indirectly affected by changes to screenWidthDp and screenHeightDp on close-to-square devices.
• Display.getSize(Point) is indirectly affected by the changes in Configuration. This was deprecated beginning in API level 30.
• Display.getMetrics() has already worked like this since API level 33.

elegantTextHeight 屬性預設值為 true

For apps targeting Android 15 (API level 35), the elegantTextHeight TextView attribute becomes true by default, replacing the compact font used by default with some scripts that have large vertical metrics with one that is much more readable. The compact font was introduced to prevent breaking layouts; Android 13 (API level 33) prevents many of these breakages by allowing the text layout to stretch the vertical height utilizing the fallbackLineSpacing attribute.

In Android 15, the compact font still remains in the system, so your app can set elegantTextHeight to false to get the same behavior as before, but it is unlikely to be supported in upcoming releases. So, if your app supports the following scripts: Arabic, Lao, Myanmar, Tamil, Gujarati, Kannada, Malayalam, Odia, Telugu or Thai, test your app by setting elegantTextHeight to true.

針對複雜字母形狀變更 TextView 寬度

在舊版 Android 中，部分草書字型或形狀複雜的語言，可能會在前一個或下一個字元的區域中繪製字母。在某些情況下，這類信件會在開頭或結尾處遭到裁切。自 Android 15 起，TextView 會分配寬度，以便繪製這類字母的空間，並允許應用程式要求左側額外的邊框間距，以防裁剪。

由於這項變更會影響 TextView 決定寬度的做法，因此如果應用程式指定 Android 15 (API 級別 35) 以上版本，TextView 預設會分配更多寬度。您可以在 TextView 上呼叫 setUseBoundsForWidth API，啟用或停用這項行為。

由於新增左邊邊框間距可能會導致現有版面配置不對齊，因此即使應用程式指定 Android 15 以上版本，也不會預設新增邊框間距。不過，您可以呼叫 setShiftDrawingOffsetForStartOverhang 新增額外的邊框間距，避免發生裁剪情形。

以下範例說明這些變更如何改善部分字型和語言的文字版面配置。

以草書字型顯示的英文文字標準版面配置。部分字母會遭到裁剪。以下是對應的 XML：

<TextView
    android:fontFamily="cursive"
    android:text="java" />

相同英文文字的版面配置，具有額外寬度和邊框間距。以下是對應的 XML：

<TextView
    android:fontFamily="cursive"
    android:text="java"
    android:useBoundsForWidth="true"
    android:shiftDrawingOffsetForStartOverhang="true" />

泰文的標準版面配置。部分字母遭到裁剪。 以下是對應的 XML：

<TextView
    android:text="คอมพิวเตอร์" />

相同泰文文字的版面配置，並增加寬度和邊框間距。以下是對應的 XML：

<TextView
    android:text="คอมพิวเตอร์"
    android:useBoundsForWidth="true"
    android:shiftDrawingOffsetForStartOverhang="true" />

EditText 的地區設定預設行高

在 Android 先前版本中，文字版面配置會拉伸文字高度，以符合與目前語言代碼相符的字型行高。舉例來說，如果內容是日文，由於日文字型的行高略大於拉丁字型，因此文字高度會稍微變高。不過，儘管行高有這些差異，EditText 元素的大小仍保持一致，不受使用語言代碼影響，如下圖所示：

針對指定 Android 15 (API 級別 35) 的應用程式，現在會為 EditText 保留最小行高，以便與指定語言代碼的參考字型相符，如以下圖片所示：

如有需要，應用程式可以將 useLocalePreferredLineHeightForMinimum 屬性指定為 false，藉此還原先前的行為，並使用 Kotlin 和 Java 中的 setMinimumFontMetrics API 設定自訂的垂直最小指標。

相機和媒體

Android 15 會針對指定 Android 15 以上版本為目標版本的應用程式，對攝影機和媒體行為做出以下變更。

要求音訊焦點的限制

指定 Android 15 (API 級別 35) 為目標版本的應用程式必須是頂層應用程式，或執行前景服務，才能要求音訊焦點。如果應用程式在未符合上述任一規定的情況下嘗試要求焦點，則呼叫會傳回 AUDIOFOCUS_REQUEST_FAILED。

如要進一步瞭解音訊焦點，請參閱「管理音訊焦點」。

更新非 SDK 限制

基於與 Android 開發人員合作及最新的內部測試，Android 15 包含更新後的受限制非 SDK 介面清單。在限制非 SDK 介面之前，我們盡可能確保公開替代方案的可得性。

如果您的應用程式並未以 Android 15 為目標版本，則此處所述的某些變更可能不會立即對您造成影響。不過，雖然應用程式可以存取某些非 SDK 介面 (視應用程式的目標 API 級別而定)，但使用任何非 SDK 方法或欄位時，均可能面臨應用程式故障的高度風險。

如果不確定應用程式是否使用非 SDK 介面，您可以測試應用程式來確認。如果您的應用程式仰賴非 SDK 介面，則建議您開始規劃遷移至 SDK 替代方案。不過，我們瞭解有些應用程式可使用非 SDK 介面運作。如果您除了為應用程式中的某個功能使用非 SDK 介面外，已別無他法，則應要求新的公用 API。

To learn more about the changes in this release of Android, see Updates to non-SDK interface restrictions in Android 15. To learn more about non-SDK interfaces generally, see Restrictions on non-SDK interfaces.