Manage fence callbacks

  • Once a fence is registered, your app needs to add a callback to respond when the fence is triggered.

  • You can add callbacks using a subclass of BroadcastReceiver to handle Intent methods from fences.

  • A subclass of BroadcastReceiver like FenceReceiver can implement onReceive() to handle intents from fences and extract the fence state using FenceState.extract().

Once a fence is registered, your app must add a callback to respond when the fence is triggered. You can do this with the use of a subclass of BroadcastReceiver to handle Intent methods from fences.

Before you add callbacks to a fence, you must first register the fence.

Create a subclass of BroadcastReceiver

The following example shows the FenceReceiver class, which extends BroadcastReceiver. The class implements the BroadcastReceiver.onReceive() callback method to handle all Intent methods that originate from fences created by your app. When an Intent is received, the FenceState.extract() method is used to get the fence state and pass it to the callback.

public class FenceReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {

        FenceState fenceState = FenceState.extract(intent);

        if (TextUtils.equals(fenceState.getFenceKey(), FENCE_KEY)) {
            String fenceStateStr;
            switch (fenceState.getCurrentState()) {
                case FenceState.TRUE:
                    fenceStateStr = "true";
                    break;
                case FenceState.FALSE:
                    fenceStateStr = "false";
                    break;
                case FenceState.UNKNOWN:
                    fenceStateStr = "unknown";
                    break;
                default:
                    fenceStateStr = "unknown value";
            }
            mLogFragment.getLogView().println("Fence state: " + fenceStateStr);
        }
    }
}