• Project Description:
We were required to write an app for Android, the app is a remote control for a joystick for FlightGear - flight simulator.
The app was written in Kotlin, edit in android studio IDE and use MVVM architecture.
The app allows the user to connect as a client to the FG server and send command strings through this connection,
these commands will move the plane and we will see the plane moving in the FG simulator.
• Video Link --->https://youtu.be/JOIfJQP0__0
• Presentation ---> Project Presentation.pdf
• Architecture MVVM
The project is built in an MVVM architecture.
The View - The XML file, activity_main.xml, is loaded to the view by MainActivity.kt. Joystick.kt is an independent component that is also being loaded to the view by MainActivity.kt.
Joystick.kt has a member named 'act' that implements Service, which is a functional interface with the method onChange.
When initializing a Joystick.kt instance in the MainActivity.kt in order to use it in the app, the programmer can inject the action that needs to happen when the joystick moves, in our case this action is sending the values to the Flight Gear via the Model object.
This action includes sending the values to the Model object via the MainActivity.kt. The MainActivity.kt inserts the values to the queue in the Model object, and the Model is responsible for sending the values to the Flight Gear.
The ViewModel - in this project MainActivity.kt acts as a ViewModel. It is responsible for adding the listeners to the seek bars, which in turn inserts the values of the seek bars to the queue in the Model object whenever their values are chenged by the user in the view layer.
The ViewModel is also responsible for the connect button - it gets the values of the requested IP and port number from the relevant elements in the xml file, and sends them to the init method of the Model object.
The Model - The MOdel object is responsible for establishing the connection to the Flight Gear and sending values to the simulator via a queue according to the users' actions.
• Preliminary requirements
Install the FlightGear ,flight simulator, which we know from Exercise 1 in this semester.
• Operating instructions
For detailed running instructions, watch the "Project Presentation" that attached to the Git.
• Connection information
The Android emulator runs on another computer, if we will give the Android app the localhost (127.0.0.1) as the IP for the connection,
it will not found anything there because it does not run on the same computer that the FG run on.
Therefore we have to give to the Android app the IP of the computer on the network - the local network.
For more details you can look on the "Project Presentation" that attached to the Git.
In the project we used object active, the connection with the sever made in a different thread.
We have a thread-pool with 2 threads in it.
One thread will "run the all project" - get information from the user (if the user moves the joystick or the seek-bars) and push the right command to the queue (set the command).
The second thread is responsible of the connection with the server and to execute the command (pulls command out from the queue and sends it to the server) - classic object active.
If the all project was running on one thread, because sending the commands to the server is an IO operation we might stuck the user - so separation prevents the user from waiting for the IO to end, it’s happens in parallel.
• class diagram
