If you write command line applications (something with main(java.langString[])) then you tend to always build up the same boiler plate code. This module provides a abstarct class InvokableAdapter for that boiler plate code. It is a defautl implementation of Invokable. Subclass the adapter and put your application code in Invokable#run() and implement a basci main method. See the Javadoc for example code.
The Invokable also provides an abstraction for IO: IOStreams with an interface IO. This makes it easy to mock out IO for testing.
It also provides a mechanism to add shutdown hooks: Runnables executed if the JVM is stoped by ctrl + c.
Example:
public final class MyApp extends InvokableAdapter {
public MyApp(final String[] args) {
super(args);
}
public static void main(final String[] args) {
InvokableAdapter.main(new MyApp(args));
}
@Override
public void execute() throws Exception {
registerShutdownHook(new Runnable() {
@Override
public void run() {
// Your shutdown code goes here.
}
});
// Your application code here.
}
}
ApplicationException are used to signal application abbort on abnormal internal errors during execution. The exit code implementation of the system module is responsible on the System#exit(int) behaviour. Typically you want your application exit with an proper exit value. You can pass that value to the thrown exception. On the other hand you don’t want to exit the JVM realy in testing environment. For that purose there is a null exiter implementation available. See system module for more information.