Fixed-size collections in .NET Printing Data Matrix barcode in .NET Fixed-size collections

Fixed-size collections using barcode development for vs .net control to generate, create datamatrix 2d barcode image in vs .net applications. Java Platform We have seen tha VS .NET gs1 datamatrix barcode t classes like ArrayList conveniently allow us to create collections containing an arbitrary number of objects. The Java library contains more collections like this, and we will look at some of the others in the next chapter.

Such collections are powerful both because we do not need to know in advance how many items will be stored in them, and because it is possible to vary the number of items they hold. However, some applications are different in that we do know in advance how many items we wish to store in a collection, and that number typically remains fixed for the life of the collection. In such circumstances, we have the option to choose to use a specialized fixed-size collection object to store the items.

. [concept box: ar ray] A fixed-size collection is called an array. While the fixed-size nature of arrays can be a significant disadvantage in many situations, they do have at least two compensating advantages over the flexible-size collection classes: Access to the items held in an array is often more efficient than access to the items in a comparable flexible-size collection..

Arrays are able ECC200 for .NET to store objects or primitive type values. Flexible-size collections can only store objects.

Another distinctive feature of arrays is that they have special syntactic support in Java accessing them uses a custom syntax different from the usual method calls. The reason for this is mostly historical: arrays are the oldest collection structure in programming languages, and syntax for dealing with arrays has developed over many decades. Java uses the same syntax established in other programming languages to keep things simple for programmers who are used to arrays already, even though it is not consistent with the rest of the language syntax.

In the following sections we will show how arrays can be used to maintain collections of fixed-size. We will also introduce a new loop structure that is often closely associated with arrays the for loop. 4.

10.1 A log-file analyzer. Web servers typi cally maintain log files of client accesses to the web pages that they store. Given suitable tools, these logs enable web service managers to extract and analyze useful information such as: Which are the most popular pages they provide. Whether other sites appear to have broken links to this site s pages.

How much data is being delivered to clients. The busiest periods over the course of a day, or week, or month..

Such information Visual Studio .NET DataMatrix might help managers to determine, for instance, whether they need to upgrade to more powerful server machines, or when the quietest periods are in order to schedule maintenance activities. The weblog-analyzer project contains an application that performs an analysis of data from such a web server.

The server writes a log line to a file each time an access is made. A sample log file called weblog.txt is provided in the project folder.

Each line records the date and time of the access in the following format:. year month day hour minute For instance, th .net framework Data Matrix barcode e line below records an access at 03:45am on 7th June 2002:. 2002 06 07 03 45. The project cons .NET Data Matrix ECC200 ists of four classes: LogAnalyzer, LogReader, LogEntry , and LoglineTokenizer. We will spend most of our time looking at the LogAnalyzer class as it contains examples of both creating and using an array (Figure 45).

Later. exercises will e ncourage you to examine and modify LogEntry because it also uses an array. The LogReader and LogLineTokenizer classes use features of the Java language that we have not yet covered, so we will not explore those in detail..

/** * Read web s Data Matrix for .NET erver data and analyse * hourly access patterns. * * @author David J.

Barnes and Michael K lling. * @version 2001.12.

31 */ public class LogAnalyzer { // Array to store the hourly access counts. private int[] hourCounts; // Use a LogfileReader to access the data. private LogfileReader reader; /** * Create an object to analyze hourly web accesses.

*/ public LogAnalyzer() { // Create the array object to hold the hourly // access counts. hourCounts = new int[24]; // Create the reader to obtain the data. reader = new LogfileReader(); } /** * Analyze the hourly access data from the log file.

*/ public void analyzeHourlyData() { while(reader.hasMoreEntries()) { LogEntry entry = reader.nextEntry(); int hour = entry.

getHour(); hourCounts[hour]++; } } /** * Print the hourly counts. * These should have been set with a prior * call to analyzeHourlyData. */ public void printHourlyCounts() { System.

out.println("Hr: Count"); for(int hour = 0; hour < hourCounts.length; hour++) { System.

out.println(hour + ": " + hourCounts[hour]); } } /** * Print the lines of data read by the LogfileReader */ public void printData() { reader.printData(); }.

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