The chance that the stack should be complete on a push is a controversy for the underlying info constitution, now not the gathering. Conceptually talking, there isn't any complete stack. Now we all know that Exceptions fifty one 52 C HA PT ER three Collections this isn't truth and that every one info constructions will finally achieve a restrict. notwithstanding, even if this actual restrict is reached, the stack isn't really complete; simply the information constitution that implements the stack is complete. we'll talk about ideas for dealing with this case as we enforce our stack within the subsequent part. What if the stack is empty on a pop? this is often an excellent case that has to do with the matter and never the underlying info constitution. In our postfix evaluate instance, if we try to pop operands and there usually are not operands to be had at the stack, our postfix expression used to be now not correctly shaped. it is a ideal case the place the gathering must file the exception and the appliance then needs to interpret that exception in context. The 3rd case is both attention-grabbing. What if the stack holds a couple of worth on the finishing touch of the overview? From the perErrors and exceptions symbolize unspective of the stack assortment, this isn't an exception. even if, ordinary or invalid processing. from the point of view of the appliance, this can be a challenge that suggests once more that the postfix expression was once no longer good shaped. since it won't generate an exception from the gathering, it is a situation for which the appliance needs to attempt. okay E Y CO N C E PT A software should be designed to technique an exception in a single of 3 methods: ■ now not deal with the exception in any respect. ■ deal with the exception the place it happens. ■ deal with the exception at one other aspect within the software. We discover each one of those techniques within the following sections. Exception Messages If an exception isn't dealt with in any respect by way of this system, this system will terminate (abnormally) and convey a message that describes what exception happened and the place within the software it was once produced. the data linked to an exception is frequently beneficial in monitoring down the reason for an issue. Let’s examine the output of an exception. An ArithmeticException is thrown while an invalid mathematics operation is tried, similar to dividing through 0. whilst that exception is thrown, if there isn't any code within the application to deal with the exception explicitly, this system terminates and prints a message just like the subsequent: Exception in thread "main" java. lang. ArithmeticException: / via 0 at 0. major (Zero. java:17) the 1st line of the exception output shows which exception used to be thrown and gives a few information regarding why it used to be thrown. the rest line or traces are the decision stack hint, which shows the place the exception happened. as a consequence, there 3. 6 Exceptions is just one line within the name stack hint, yet there's numerous, looking on the place the exception originated within the application. the 1st line of the hint shows the strategy, dossier, and line quantity the place the exception happened.