Determine and monitor the docking state and type

Android devices can be docked into several different kinds of docks. These include car or home docks and digital versus analog docks. The dock-state is typically closely linked to the charging state as many docks provide power to docked devices.

How the dock-state of the phone affects your update rate depends on your app. You may choose to increase the update frequency of a sports center app when it's in the desktop dock, or disable your updates completely if the device is car docked. Conversely, you may choose to maximize your updates while car docked if your background service is updating traffic conditions.

The dock state is also broadcast as a sticky Intent, allowing you to query if the device is docked or not, and if so, in which kind of dock.

Determine the current docking state

The dock-state details are included as an extra in a sticky broadcast of the ACTION_DOCK_EVENT action. Because it's sticky, you can simply call registerReceiver(), passing in null as the broadcast receiver. The following snippet shows how to complete this process:

val dockStatus: Intent? = IntentFilter(Intent.ACTION_DOCK_EVENT).let { ifilter ->
    context.registerReceiver(null, ifilter)
}

IntentFilter ifilter = new IntentFilter(Intent.ACTION_DOCK_EVENT);
Intent dockStatus = context.registerReceiver(null, ifilter);

You can extract the current docking status from the EXTRA_DOCK_STATE extra:

val dockState: Int = dockStatus?.getIntExtra(EXTRA_DOCK_STATE, -1) ?: -1
val isDocked: Boolean = dockState != Intent.EXTRA_DOCK_STATE_UNDOCKED

int dockState = dockStatus.getIntExtra(EXTRA_DOCK_STATE, -1);
boolean isDocked = dockState != Intent.EXTRA_DOCK_STATE_UNDOCKED;

Determine the current dock type

If a device is docked, it can be docked in any one of four different type of dock:

• Car
• Desk
• Low-End (Analog) Desk
• High-End (Digital) Desk

Note that the latter two options were only introduced to Android in API level 11, so it's good practice to check for all three where you are only interested in the type of dock rather than it being digital or analog specifically:

val isCar: Boolean = dockState == EXTRA_DOCK_STATE_CAR
val isDesk: Boolean = dockState == EXTRA_DOCK_STATE_DESK
        || dockState == EXTRA_DOCK_STATE_LE_DESK
        || dockState == EXTRA_DOCK_STATE_HE_DESK

boolean isCar = dockState == EXTRA_DOCK_STATE_CAR;
boolean isDesk = dockState == EXTRA_DOCK_STATE_DESK ||
                 dockState == EXTRA_DOCK_STATE_LE_DESK ||
                 dockState == EXTRA_DOCK_STATE_HE_DESK;