Android Wear: small gist to start an Activity on the mobile handheld from the Android Wear device.

mobile-AndroidManifest.xml

        <service android:name=".ListenerServiceFromWear">
            <intent-filter>
                <action android:name="com.google.android.gms.wearable.BIND_LISTENER" />
            </intent-filter>
        </service>

mobile-gradle.build

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    wearApp project(':wear')
    compile 'com.google.android.gms:play-services-wearable:+'
}

mobile-ListenerServiceFromWear.java

public class ListenerServiceFromWear extends WearableListenerService {

    private static final String HELLO_WORLD_WEAR_PATH = "/hello-world-wear";

    @Override
    public void onMessageReceived(MessageEvent messageEvent) {

        /*
         * Receive the message from wear
         */
        if (messageEvent.getPath().equals(HELLO_WORLD_WEAR_PATH)) {

            Intent startIntent = new Intent(this, MyActivity.class);
            startIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(startIntent);
        }

    }

}

wear-AndroidManifest.xml

 <meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version" />

wear-gradle.build

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile "com.google.android.support:wearable:1.0.+"
    compile 'com.google.android.gms:play-services-wearable:+'
}

wear-LaunchActivity.java

public class LaunchActivity extends Activity implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener {

    Node mNode; // the connected device to send the message to
    GoogleApiClient mGoogleApiClient;
    private static final String HELLO_WORLD_WEAR_PATH = "/hello-world-wear";
    private boolean mResolvingError=false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_launch);

        //Connect the GoogleApiClient
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(Wearable.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();

        //UI elements with a simple CircleImageView
        final WatchViewStub stub = (WatchViewStub) findViewById(R.id.watch_view_stub);
        stub.setOnLayoutInflatedListener(new WatchViewStub.OnLayoutInflatedListener() {
            @Override
            public void onLayoutInflated(WatchViewStub stub) {
             CircledImageView mCircledImageView = (CircledImageView) stub.findViewById(R.id.circle);
             
             //Listener to send the message (it is just an example)
             mCircledImageView.setOnClickListener(new View.OnClickListener() {
                 @Override
                 public void onClick(View v) {
                        sendMessage();
                 }
             });
            }
        });
    }


    /**
     * Send message to mobile handheld
     */
    private void sendMessage() {

        if (mNode != null && mGoogleApiClient!=null && mGoogleApiClient.isConnected()) {
            Wearable.MessageApi.sendMessage(
                    mGoogleApiClient, mNode.getId(), HELLO_WORLD_WEAR_PATH, null).setResultCallback(

                    new ResultCallback<MessageApi.SendMessageResult>() {
                        @Override
                        public void onResult(MessageApi.SendMessageResult sendMessageResult) {

                            if (!sendMessageResult.getStatus().isSuccess()) {
                                Log.e("TAG", "Failed to send message with status code: "
                                        + sendMessageResult.getStatus().getStatusCode());
                            }
                        }
                    }
            );
        }else{
            //Improve your code
        }

    }

    @Override
    protected void onStart() {
        super.onStart();
        if (!mResolvingError) {
            mGoogleApiClient.connect();
        }
    }

    /*
     * Resolve the node = the connected device to send the message to
     */
    private void resolveNode() {

        Wearable.NodeApi.getConnectedNodes(mGoogleApiClient).setResultCallback(new ResultCallback<NodeApi.GetConnectedNodesResult>() {
            @Override
            public void onResult(NodeApi.GetConnectedNodesResult nodes) {
                for (Node node : nodes.getNodes()) {
                   mNode = node;
                }
            }
        });
    }


    @Override
    public void onConnected(Bundle bundle) {
        resolveNode();
    }

    @Override
    public void onConnectionSuspended(int i) {
        //Improve your code
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        //Improve your code
    }
}

Thank you for this nice example. Works like a charm!

But please keep in mind: The Manifest IntentFilter BIND_LISTENER is now deprecated. You should not use:
<action android:name="com.google.android.gms.wearable.BIND_LISTENER" />
anymore.
More informations here: http://android-developers.blogspot.de/2016/04/deprecation-of-bindlistener.html

The service declaration in the Manifest should look like this now:

        <service android:name=".ListenerServiceFromWear">
            <intent-filter>
                <action android:name="com.google.android.gms.wearable.MESSAGE_RECEIVED" />
                <data android:scheme="wear" android:host="*"
                    android:path="/hello-world-wear" />
            </intent-filter>
        </service>

This is the only working app currently on google which call handheld activity from wearable. Thanks.