I want to close and then restart a already running application (automatically) that I am making, by clicking a button or something like that, I want to do that for the purpose of re-launching the application in an other language, I'm new to JavaFx and Java in general, please can you give me a solution for this problem ?
This question lacks details. You did mention a JavaFX application but it is important to know how that application is being deployed. Is it running in the web browser, as a java webstart application, a stand-alone jar, or a self-contained native application? How are you starting the application to begin with? Having the answer to these questions will make it easier to answer your question with specifics.
While the following example is not JavaFX, the approach used here would work for some of the ways in which a JavaFX application can be deployed. One approach for restarting an application that works nicely is to start the application from a script. Inside the script would be a while loop that continually restarts the program based on the program exit code. Here is an example for a bash shell script which starts IntelliJ on a Linux platform:
while true ; do eval "$JDK/bin/java" $ALL_JVM_ARGS -Djb.restart.code=88 $MAIN_CLASS_NAME $* test $? -ne 88 && break done
In this example, the startup script is passing "jb.restart.code" as an application parameter. If IntelliJ wishes to restart, it will return that value 88 as the exit code. The script observes the application exit code, and restarts the application if the value is 88.
This approach works well on most platforms, but requires the application to be initiated via a script.
One solution is to pass commandline and working dir in your start script to your main() method. Using ProcessBuilder you then can restart the appliation. Another possibility is to start the whole application in a custom classloader (e.g. Spring project has suitable classloaders in their source base), you then can basically restart by starting your main in anouther classloader, however you then need proper housekeeping to free threads and resources of the first instance.