I have an application in java, in which i try to ensure that the if anybody exits codes System.exit() in the code , an listener should be called to do some stuff like logging message and releasing the resources ...
How can i implement it, any suggestion/approach is welcome.
The following class provides a method assertExits(int expectedStatus, Executable executable) which asserts that System. exit() is called with a specified status value, and the test can continue after it. It works the same way as JUnit 5 assertThrows . It also respects an existing security manager.
System. exit() method. This method terminates the currently running Java Virtual Machine(JVM). It takes an argument “status code” where a non zero status code indicates abnormal termination.
The main alternative is Runtime. getRuntime(). halt(0) , described as "Forcibly terminates the currently running Java virtual machine". This does not call shutdown hooks or exit finalizers, it just exits.
No. System. exit(0) doesn't return, and the finally block is not executed.
The Runtime.addShutdownHook
method can be used to add a shutdown hook, which is basically a unstarted Thread
, which executes on shutdown of the Java Virtual Machine.
However, this is territory that should to be tread carefully, as it is being performed at a very sensitive time of the JVM's life cycle. From the API Specifications for the Runtime.addShutdownHook
method:
Shutdown hooks run at a delicate time in the life cycle of a virtual machine and should therefore be coded defensively. They should, in particular, be written to be thread-safe and to avoid deadlocks insofar as possible.
In any event, be sure to read up a bit on how shutdown hooks work, as they probably should not be approached without some good preparation. Be sure to carefully read the API Specification for the Runtime.addShutdownHook
method.
Here's are a couple articles I found from searching for information for this answer:
Shutdown Hooks -- it shows a little example of how a shutdown hook is added for logging at shutdown.
Design of the Shutdown Hooks API -- addresses some design decisions of shutdown hooks in a question and answer style.
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