Java - Exceptions

Java module J712

Exceptions

Exercises, examples and other material relating to training module J712. This topic is presented on public courses Learning to Program in Java, Java Bootcamp, Java Programming for the Web

Your program is affected by the environment around it. Its performance will vary depending on aspects as diverse as user inputs and the availability (or lack) of a network service. Java provides you with exceptions, which are a mechanism through which you trap and handle behaviours that differ from the norm.

Related technical and longer articles

errors v exceptions

Articles and tips on this subject		updated
3045	After Course Resources - do we publish sample answers. Example from Java Exceptions module. At the end of each module on our courses, there's an exercise for the delegates. It lets them make use of many of the elements they've learned about to consolidate their knowledge. And it helps me evaluate, as they work through the exercise, how they are progressing; I can "mop up" any major elements ...	2010-11-13 (longest)
3048	String handling - from first steps to practical examples Initial String handling examples on a training course are sometimes a bit mundane - and that's because we have to cover some of the basics like "what is a string" before we start reading them in useful quantities from files, databases, or web resources. But it's important to get those basics understood ...	2010-11-13
2862	Fail Safe Error Handling in Java via Exceptions "What could possibly go wrong?" ... The usual answer from a cynic is "anything, and usually at the most inconvenient time, and in the most unexpected way!". So checking for routine errors in your program code is a good start, but it doesn't go far enough; you need to be able to handle errors which are ...	2010-07-09
2622	Handling unusual and error conditions - exceptions "I can't answer that question in the way you expect" ... that's something that may be said to you occasionally - you ask someone what suit a playing card is that they're holding and they cannot tell you because it is a joker, or you ask what number is written on a piece of paper when the paper is blank. The ...	2010-02-03
2420	Exceptions in Java - why and how Although it's common practise to include a static main test program in a class, it's something that newcomers can have some difficulty following ... so we don't do it too early on the course - we keep classes and programs that use those classes (even if they are just test programs) each in their own ...	2009-09-25
1875	What are exceptions - Python based answer How do you check for run time errors in your program? You'll include tests with if statements in almost every program you write, to ensure that user entered data is reasonable / as you would expect ... but you will also need to do more that that. You'll need to check whether a system function has run ...	2008-11-08
1066	Final, Finally and Finalize - three special words in Java A final method or variable is one that can't be overridden - you can define a method as final within a class to ensure that any extensions to the class don't replace it. If you add a finally block onto the end of a try / catch exception handler, you're defining a block of code that will be run if the ...	2007-02-05

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Examples from our training material

Bikini.java	Practical Exception Handling Example
E1.java	Class to which to add exception handling during practicals
E1a.java	Sample answer - handling exceptions on reading use input
Jane.java	Define your own exception class
Keira.java	try, catch, finally - full example
card_7.java	for neston demo - interface card
neston.java	First example of an exception
playing_card_7.java	class of playing_card, used in "neston"
suspect_card_7.java	class used within "neston" demonstration
wadswick.java	Sample program that will throw an exception, not catch it, and fail

Background information

This module is available under an Open Training Notes License for free download from http://www.training-notes.co.uk.

Topics covered in this module

"trying" and "catching".
"throwing".
"finally".
Defining your own exceptions.

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