[null,null,[],[],[],null,["# Physical buttons\n\nA wearable device typically contains multiple physical buttons, also known as _stems_. Wear OS\ndevices always have, at minimum, one button: the power button. Beyond that, zero or more\nmultifunction buttons might be present.\n\n\nIn your app, you can assign multifunction buttons to actions. For example, a fitness app\nmight start or pause a workout using multifunction buttons:\n\n**Note:** Wear OS 3.0 reserves two buttons for the OS, while\nWear OS 2.0 reserves only one. This reduces the number of buttons you can assign\nactions to. \n\nFor suitable use cases and design considerations, review the\n[Wear OS design principles](/training/wearables/design).\n\n\nThis guide describes how to retrieve information about available multifunction buttons on\na device and how to process button presses.\n\nButton metadata\n---------------\n\n\nTo get extra information about the buttons on a device, use the API defined in the\n[Wear Input](/reference/androidx/wear/input/package-summary) AndroidX library. Add the\nfollowing dependency in your app module's `build.gradle` file: \n\n```groovy\ndependencies {\nimplementation \"androidx.wear:wear-input:1.0.0\"\n}\n```\n\n### Number of buttons\n\n\nTo find out how many buttons are available on the device, use the\n[`WearableButtons.getButtonCount()`](/reference/android/support/wearable/input/WearableButtons#getButtonCount(android.content.Context)) method. This method includes the power button,\nso if the method returns a value greater than one, then there are multifunction buttons available\nfor use. To get an accurate count of assignable multifunction buttons, subtract\none from the count, since the first button is always the power button.\n\n### Keycodes for button presses\n\n\nEach button is mapped to an `int` constant from the [KeyEvent](https://developer.android.com/reference/android/view/KeyEvent.html)\nclass, as shown in the following table:\n\n| Button | KeyEvent |\n|------------------------|------------------|\n| Multifunction button 1 | `KEYCODE_STEM_1` |\n| Multifunction button 2 | `KEYCODE_STEM_2` |\n| Multifunction button 3 | `KEYCODE_STEM_3` |\n\n\nThe following example code shows how to get the available button\ncount: \n\n### Kotlin\n\n```kotlin\nval count = WearableButtons.getButtonCount(context)\n\nif (count \u003e 1) {\n // There are multifunction buttons available\n}\n\nval buttonInfo = WearableButtons.getButtonInfo(activity, KeyEvent.KEYCODE_STEM_1)\n\nif (buttonInfo == null) {\n // KEYCODE_STEM_1 is unavailable\n} else {\n // KEYCODE_STEM_1 is present on the device\n}\n```\n\n### Java\n\n```java\nint count = WearableButtons.getButtonCount(context);\n\nif (count \u003e 1) {\n // There are multifunction buttons available\n}\n\nWearableButtons.ButtonInfo buttonInfo =\n WearableButtons.getButtonInfo(activity, KeyEvent.KEYCODE_STEM_1);\n\nif (buttonInfo == null) {\n // KEYCODE_STEM_1 is unavailable\n} else {\n // KEYCODE_STEM_1 is present on the device\n}\n```\n\nHandle button presses\n---------------------\n\n\nThere are a number of possible button keycodes that your app can handle:\n\n- `KEYCODE_STEM_1`\n- `KEYCODE_STEM_2 `\n- `KEYCODE_STEM_3`\n\n\nYour app can receive these key codes and convert them to specific in-app actions.\n\n\nTo handle a button press, implement the\n[`onKeyDown()`](/reference/android/app/Activity#onKeyDown(int,%20android.view.KeyEvent)) method.\n\n\nFor example, this implementation responds to button presses to control\nactions in an app: \n\n### Kotlin\n\n```kotlin\n// Activity\noverride fun onKeyDown(keyCode: Int, event: KeyEvent): Boolean {\n return if (event.repeatCount == 0) {\n when (keyCode) {\n KeyEvent.KEYCODE_STEM_1 -\u003e {\n // Do stuff\n true\n }\n KeyEvent.KEYCODE_STEM_2 -\u003e {\n // Do stuff\n true\n }\n KeyEvent.KEYCODE_STEM_3 -\u003e {\n // Do stuff\n true\n }\n else -\u003e {\n super.onKeyDown(keyCode, event)\n }\n }\n } else {\n super.onKeyDown(keyCode, event)\n }\n}\n```\n\n### Java\n\n```java\n@Override\n// Activity\npublic boolean onKeyDown(int keyCode, KeyEvent event){\n if (event.getRepeatCount() == 0) {\n if (keyCode == KeyEvent.KEYCODE_STEM_1) {\n // Do stuff\n return true;\n } else if (keyCode == KeyEvent.KEYCODE_STEM_2) {\n // Do stuff\n return true;\n } else if (keyCode == KeyEvent.KEYCODE_STEM_3) {\n // Do stuff\n return true;\n }\n }\n return super.onKeyDown(keyCode, event);\n}\n```\n\nDetermine the button positions\n------------------------------\n\n\nThe AndroidX Library provides two methods that describe the location of a button:\n\n- [`WearableButtons.getButtonLabel()`](/reference/android/support/wearable/input/WearableButtons#getButtonLabel(android.content.Context, int)) returns a localized string describing the general placement of the button on the device.\n- [`WearableButtons.getButtonIcon()`](/reference/android/support/wearable/input/WearableButtons#getButtonIcon(android.content.Context, int)) returns an icon representing the general placement of the button on the device.\n\n**Note:** We recommend that you avoid using textual descriptors\nwhen describing buttons and their functions. Use visual indicators instead. However, there may\nbe some cases where describing a button makes more sense.\n\n\nThe previous methods were designed for simple descriptions. If these APIs don't suit your app's\nneeds, you can also use the `WearableButtons.getButtonInfo()` API to get the\nlocation of the button on the screen and handle it in a more customized way. For more\ninformation on the APIs, see the\n[Wear API reference](/reference/android/support/wearable/input/package-summary)."]]
