visual basic barcode program 16. // Some other unguarded (normal, non-risky) code begins here in Java

Paint PDF-417 2d barcode in Java 16. // Some other unguarded (normal, non-risky) code begins here

15. 16. // Some other unguarded (normal, non-risky) code begins here
Scanning PDF-417 2d Barcode In Java
Using Barcode Control SDK for Java Control to generate, create, read, scan barcode image in Java applications.
Encode PDF417 In Java
Using Barcode drawer for Java Control to generate, create PDF417 image in Java applications.
In this pseudocode example, lines 2 through 5 constitute the guarded region that is governed by the try clause. Line seven is an exception handler for an exception of type MyFirstException. Line 12 is an exception handler for an exception of type MySecondException. Notice that the catch blocks immediately follow the try block. This is a requirement; if you have one or more catch blocks, they must immediately follow the try block. Additionally, the catch blocks must all follow each other, without any other statements or blocks in between. Also, the order in which the catch blocks appear matters, as we ll see a little later. Execution starts at line 2. If the program executes all the way to line 5 with no exceptions being thrown, execution will transfer to line 15 and continue downward. However, if at any time in lines 2 through 5 (the try block) an exception is thrown of type MyFirstException, execution will immediately transfer to line 8. Lines 8 through 10 will then be executed so that the entire catch block runs, and then execution will transfer to line 15 and continue. Note that if an exception occurred on, say, line 3 of the try block, the rest of the lines in the try block (3 through 5) would never be executed. Once control jumps to the catch block, it never returns to complete the balance of the try block. This is exactly what you want, though. Imagine your code looks something like this pseudocode:
Recognize PDF417 In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
Make Bar Code In Java
Using Barcode maker for Java Control to generate, create barcode image in Java applications.
try { getTheFileFromOverNetwork readFromTheFileAndPopulateTable } catch(CantGetFileFromNetwork) { useLocalFileInstead }
Scan Barcode In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
PDF 417 Printer In Visual C#
Using Barcode creator for Visual Studio .NET Control to generate, create PDF 417 image in .NET framework applications.
The preceding pseudocode demonstrates how you typically work with exceptions. Code that s dependent on a risky operation (as populating a table with file data is dependent on getting the file from the network) is grouped into a try block in such a way that if, say, the first operation fails, you won t continue trying to run other code that s guaranteed to also fail. In the pseudocode example, you won t be able to read from the file if you can t get the file off the network in the first place. One of the benefits of using exception handling is that code to handle any particular exception that may occur in the governed region needs to be written only
PDF417 Printer In .NET
Using Barcode printer for ASP.NET Control to generate, create PDF-417 2d barcode image in ASP.NET applications.
PDF 417 Creator In .NET
Using Barcode creator for VS .NET Control to generate, create PDF-417 2d barcode image in Visual Studio .NET applications.
4: Flow Control, Exceptions, and Assertions
PDF417 Generation In Visual Basic .NET
Using Barcode generation for .NET framework Control to generate, create PDF 417 image in VS .NET applications.
UCC - 12 Printer In Java
Using Barcode creation for Java Control to generate, create UPCA image in Java applications.
once. Returning to our earlier code example, there may be three different places in our try block that can generate a MyFirstException, but wherever it occurs it will be handled by the same catch block (on line 7). We ll discuss more benefits of exception handling near the end of this chapter.
Drawing Data Matrix 2d Barcode In Java
Using Barcode encoder for Java Control to generate, create Data Matrix ECC200 image in Java applications.
Encoding Code 128C In Java
Using Barcode encoder for Java Control to generate, create Code 128 Code Set C image in Java applications.
Using finally
Creating International Standard Book Number In Java
Using Barcode generation for Java Control to generate, create ISBN - 13 image in Java applications.
Recognize Barcode In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
Try and catch provide a terrific mechanism for trapping and handling exceptions, but we are left with the problem of how to clean up after ourselves. Because execution transfers out of the try block as soon as an exception is thrown, we can t put our cleanup code at the bottom of the try block and expect it to be executed if an exception occurs. Almost as bad an idea would be placing our cleanup code in the catch blocks. Exception handlers are a poor place to clean up after the code in the try block because each handler then requires its own copy of the cleanup code. If, for example, you allocated a network socket or opened a file somewhere in the guarded region, each exception handler would have to close the file or release the socket. That would make it too easy to forget to do cleanup, and also lead to a lot of redundant code. To address this problem, Java offers the finally block. A finally block encloses code that is always executed at some point after the try block, whether an exception was thrown or not. Even if there is a return statement in the try block, the finally block executes right after the return statement! This is the right place to close your files, release your network sockets, and perform any other cleanup your code requires. If the try block executes with no exceptions, the finally block is executed immediately after the try block completes. If there was an exception thrown, the finally block executes immediately after the proper catch block completes. Let s look at another pseudocode example:
Data Matrix 2d Barcode Reader In Visual Basic .NET
Using Barcode scanner for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
Creating Code 39 Extended In None
Using Barcode creation for Office Word Control to generate, create Code 39 Extended image in Microsoft Word applications.
1: 2: 3: 4: 5: 6: 7: 8: 9: 10: 11: 12: try { // This is the first line of the "guarded region". } catch(MyFirstException) { // Put code here that handles this error. } catch(MySecondException) { // Put code here that handles this error. } finally { // Put code here to release any resource we // allocated in the try clause.
Generating EAN13 In .NET Framework
Using Barcode drawer for .NET framework Control to generate, create European Article Number 13 image in .NET applications.
Make Code 39 Extended In None
Using Barcode printer for Excel Control to generate, create Code 39 Full ASCII image in Microsoft Excel applications.
Handling Exceptions (Exam Objectives 2.3 and 2.4)
Making UCC - 12 In None
Using Barcode maker for Excel Control to generate, create GTIN - 128 image in Office Excel applications.
EAN / UCC - 14 Creator In None
Using Barcode maker for Font Control to generate, create USS-128 image in Font applications.
Copyright © OnBarcode.com . All rights reserved.