Warning
The API presented here is still under development and may change in the future.
The Java SDK provides Java bindings to:
This SDK is based on libqi-java, which in turn uses the qi framewok, and contains additional wrapper Java-dedicated classes that can be found in this Javadoc.
| OS | Comment |
|---|---|
| Windows 32 bits | No 64 bits support. |
| Linux 32 and 64 bits | Tested with Ubuntu 12.04 LTS, but should work fine on any recent distribution. |
| Mac OS X 64 bits | |
| NAOqi OS 2.1 and higher | Running on NAO V4 and V5. |
| Android 4.0 | For ARM. |
There is one .jar per NAOqi version and platform.
This .jar will allow you to use the Aldebaran‘s C++ API or to create your own services, and run them from a remote machine or directly in the robot.
First, download the java-naoqi-sdk-<version>-<platform>.jar from the Community website. Then, use it as you would do for any 3rd party Java library:
Add the java-naoqi-sdk-<version>-<platform>.jar as an external jar in the properties of your project.
# Compile your application
javac -cp /path/to/java-naoqi-sdk-<version>-<platform>.jar YourClass.java
# Run your application
java -cp /path/to/java-naoqi-sdk-<version>-<platform>.jar:. YourClass
Warning
Java is not currently present in the system image.
However, you may install and configure Java on your robot if you wish to run your services directly in the robot.
| Step | Action |
|---|---|
| Download the JRE 32bits from the Oracle website. | |
Upload then extract it somewhere on the robot. scp jre-7u60-linux-i586.tar.gz nao@nao.local:
ssh nao@nao.local
tar xvfz jre-7u60-linux-i586.tar.gz
mkdir /home/nao/java
mv jre1.7.0_60 /home/nao/java
|
|
Copy the java-naoqi-sdk-<version>-atom jar on the robot. For instance, in: /home/nao/java/ scp java-naoqi-sdk-<version>-atom.jar nao@nao.local:/home/nao/java/
|
|
Create a sourceme file looking like: nano /home/nao/java/sourceme
export JAVA_HOME=/home/nao/java/jre
export PATH=$PATH:/home/nao/java/jre/bin
export CLASSPATH=/home/nao/java/java-naoqi-sdk-<version>-atom.jar
|
|
| Compile your code and upload the .class files to the robot. (see previous section From the command line) | |
| Run source sourceme and use the command line to run your Java application. |
There are two important concepts to know that will allow you to communicate with your robot: Application and Session.
An Application is responsible of initializing the framework and connecting it to a session. A Session is what allows you to connect services together locally or over the network.
By default, the session URL is set to tcp://127.0.0.1:9559. If you wish to change this, you can pass it as a command line argument (using –qi-url):
java -cp /path/to/java-naoqi-sdk-<version>-<platform>.jar:. YourClass --qi-url=nao.local
public static void main(String[] args) {
Application application = new Application(args);
try{
// Start the application and create a session.
application.start();
// A session has been created. It can be retrieved this way:
// application.session();
}
catch(Exception e){
// The application could not be started.
e.printStackTrace();
}
}
or in the Application constructor:
public static void main(String[] args) {
// The robotUrl is specified here
String robotUrl = "tcp://nao.local:9559";
Application application = new Application(args, robotUrl);
try{
// Start the application and create a session.
application.start();
// A session has been created. It can be retrieved this way:
// application.session();
}
catch(Exception e){
// The application could not be started.
e.printStackTrace();
}
}
Warning
The Application constructor must be called exactly once in the main Java process for the type system and the event loop to work.
In Java SDK, there are dedicated classes for each service. This means that you must create an instance of the desired service to be able to call its methods.
The example below shows how to make the robot say “Hello World” by using ALTextToSpeech.
package com.aldebaran.examples;
import com.aldebaran.qi.Application;
import com.aldebaran.qi.helper.proxies.ALTextToSpeech;
public class SayHello {
public static void main(String[] args) throws Exception {
String robotUrl = "tcp://nao.local:9559";
// Create a new application
Application application = new Application(args, robotUrl);
// Start your application
application.start();
// Create an ALTextToSpeech object and link it to your current session
ALTextToSpeech tts = new ALTextToSpeech(application.session());
// Make your robot say something
tts.say("Hello World!");
}
}
It is possible to subscribe to ALMemory events by using the ALMemory.subscribeToEvent method but with a slight different signature: an EventCallback with the expected type is needed, and a subscription ID is given in return.
The example below shows how to make the robot react every time its front tactile head sensor is touched, and to stop reacting (unsubscribe from FrontTactilTouched event) when its rear tactile head sensor has been touched.
package com.aldebaran.examples;
import com.aldebaran.qi.Application;
import com.aldebaran.qi.CallError;
import com.aldebaran.qi.Session;
import com.aldebaran.qi.helper.EventCallback;
import com.aldebaran.qi.helper.proxies.ALMemory;
import com.aldebaran.qi.helper.proxies.ALTextToSpeech;
public class ReactToEvents {
public static void main(String[] args) throws Exception {
String robotUrl = "tcp://nao.local:9559";
// Create a new application
Application application = new Application(args, robotUrl);
// Start your application
application.start();
System.out.println("Successfully connected to the robot");
// Subscribe to selected ALMemory events
ReactToEvents reactor = new ReactToEvents();
reactor.run(application.session());
System.out
.println("Subscribed to FrontTactilTouched and RearTactilTouched.");
// Run your application
application.run();
}
ALMemory memory;
ALTextToSpeech tts;
long frontTactilSubscriptionId;
public void run(Session session) throws Exception {
memory = new ALMemory(session);
tts = new ALTextToSpeech(session);
frontTactilSubscriptionId = 0;
// Subscribe to FrontTactilTouched event,
// create an EventCallback expecting a Float.
frontTactilSubscriptionId = memory.subscribeToEvent(
"FrontTactilTouched", new EventCallback<Float>() {
@Override
public void onEvent(Float arg0)
throws InterruptedException, CallError {
// 1 means the sensor has been pressed
if (arg0 > 0) {
tts.say("ouch!");
}
}
});
// Subscribe to RearTactilTouched event,
// create an EventCallback expecting a Float.
memory.subscribeToEvent("RearTactilTouched",
new EventCallback<Float>() {
@Override
public void onEvent(Float arg0)
throws InterruptedException, CallError {
if (arg0 > 0) {
if (frontTactilSubscriptionId > 0) {
tts.say("I'll no longer say ouch");
// Unsubscribing from FrontTactilTouched event
memory.unsubscribeToEvent(frontTactilSubscriptionId);
}
}
}
});
}
}
It is also possible to create and register your own service.
First, create your own QiService. For example:
package com.aldebaran.examples;
import com.aldebaran.qi.QiService;
public class HelloService extends QiService {
public String greet(String name) {
return "Hello " + name;
}
}
Then, register your service and run your application:
package com.aldebaran.examples;
import com.aldebaran.qi.Application;
import com.aldebaran.qi.DynamicObjectBuilder;
import com.aldebaran.qi.QiService;
import com.aldebaran.qi.Session;
public class MyApplication {
public static void main(String[] args) throws Exception {
String robotUrl = "tcp://nao.local:9559";
// Create a new application
Application application = new Application(args, robotUrl);
// Create an instance of your service
QiService service = new HelloService();
// Create a DynamicObjectBuilder, that will render your service
// compatible with other supported languages.
DynamicObjectBuilder objectBuilder = new DynamicObjectBuilder();
service.init(objectBuilder.object());
// Advertise the greet method contained in your HelloService service.
// You need to specify its signature.
objectBuilder.advertiseMethod("greet::s(s)", service,
"Greets the caller");
// Start your application
application.start();
// Retrieve the created session
Session session = application.session();
// Register your service in your session
session.registerService("MyHelloService", objectBuilder.object());
// Run your application
application.run();
}
}
As long as your application is running, you can call the advertised methods of your MyHelloService service as you would do for any other NAOqi service.