Determine and monitor the docking state and type

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

Your app affects the phone's update rate in the dock state. You can increase the update frequency of a sports news app when it's in the desktop dock, or disable your updates completely if the device is car docked. Conversely, you can maximize your updates while car docked if your background service is updating traffic conditions.

The dock state is also broadcast as a sticky Intent, letting you query whether the device is docked and in which kind of dock if so.

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 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 -1;
if (dockStatus != null) {
  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 of the following four different dock types:

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

The latter two options are only introduced in Android API level 11, so it's good practice to check for all three desk types when 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;