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try, catch, finally - full example
Exceptions example from a Well House Consultants training course
More on Exceptions [link]
Source code: Keira.java Module: J712
/* This is a complete example (when read in conjunction with the class "Jane"
which is in the same directory on our server) showing the running of a piece of code and the catching of a variety of exceptions - standard ones, ones you have defined yourself, etc. The example also shows you how clean up code goes in a finally block, and how a method can handle exceptions itself, or can return them (throw them up) to the calling method. */ // Exceptions ... // A "Jane" is one of our own exceptions - thrown if a number is too large public class Keira { // methods can handle their own problems or, in as here, call on their // parent to help them. (like children, really!) static int getval(String instuff) throws Exception { int result = Integer.parseInt(instuff); if (result > 40) { Jane Jones = new Jane(); throw Jones; } return result; } public static void main (String [] args) { int inval = 0; try { inval = getval(args[0]) ; } catch (Jane e) { System.out.println("I have a concern: "+e.getMessage()); inval = 39; // Force a fallback value. // No "return" do DO proceed } catch (Exception e) { System.out.println("I have a problem: "+e.getMessage()); // Should probably add type of exception to message! return; // do NOT process to rest of method } finally { // Happens whether or not we proceed! System.out.println("I'm cleaning up"); } System.out.println("SUCCESS ... Here we go ..."); System.out.println("" + inval + " + 3 is " + (inval +3)); } } /* wizard:java graham$ java Keira I have a problem: 0 I'm cleaning up wizard:java graham$ java Keira 4 I'm cleaning up SUCCESS ... Here we go ... 4 + 3 is 7 wizard:java graham$ java Keira four I have a problem: For input string: "four" I'm cleaning up wizard:java graham$ java Keira 44 I have a concern: OOhh - Tarzan! I'm cleaning up SUCCESS ... Here we go ... 39 + 3 is 42 */ Learn about this subject
This module and example are covered on the following public courses:
* Learning to Program in Java * Java Bootcamp * Java Programming for the Web Also available on on site courses for larger groups Books covering this topic
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Other Examples
This example comes from our "Exceptions" training module. You'll find a description of the topic and some
other closely related examples on the "Exceptions" module index page.
Full description of the source code
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