Conexion de una base de datos de PostgreSql 8.2 a Java

Search file directory (recursive method) with java language

Convert InputStream to byte[]

Convert java.awt.Canvas to java.awt.image.BufferedImage

Snippet for display one frame in full screen mode.

This is a simple function to check if an email is valid or not.

From a tutorial on building an RSS SAX parser on my website:

full article can be found here

Convert
java.awt.Canvas to java.awt.image.BufferedImage or java.awt.image.Image

The following script is a single interface for pre-validating any HTML form. It lets you validate your form data the way you want, while handling the rudimentary tasks itself.

1) Change just one variable to make it work with $_GET or $_POST or $_REQUEST.

2) Name which elements are 'required' all at once in a hidden HTML text input.

3) Easily provide field descriptions in hidden HTML text inputs that you can use to print error statements.

4) Call a single function to print out error statements that you can easily style with CSS.

5) It automatically checks if fields marked 'required' have been filled out.

Most of the pre-validation code is from PHP 5: Unleashed by Sams Publishing. I found it extremely useful for a recent project. Sharing it here, I removed some unnecessary functions, and tried to simplify some points.

All the comments are my own; hopefully I provided more than enough explanation.

I like to have these two methods in my toolbelt, even though it's syntactic sugar, I think it aids clarity.

A GroovyClassLoader demonstration. The given domain is a german water flow meter system; I think, you shouldn't be able to understand the domain, but you should be able to understand, how to load a Groovy class in Java via a GroovyClassLoader.

This is a very convenient way to remove all doubles from a List in Java. The only prerequisite is that the elements in the list have proper equals and hashCode methods.

It work by using the constructor of a Set that takes a Collection as an argument.

I poured the snippet in a little program so can run it straight away.

Adds any character at the given index of a string.

NOTE: Count starts from 0

This simple function simply removes the character at the given index from a string.

NOTE: The count starts from 0

create a random string of 16 chars

Function that splits a given string into sections based on the allowed length for a section. Does not split words up. Splits string on Space character (can be set to another character)

A simple snippet for using single pass DES encryption. Uses the .NET framework functions. Enjoy!

To create a chatprogram in java we need 2 classes one for Client and one for Server from which the client will be able to connect and exchange text messages. to compile the code simply type these commands in command prompt window:-
1)ipconfig(memorize the Ip address)
2)javac client.java
3)javac server.java
4)java server 10.69.23.203 (You need to type your own ip address)
5) After this you need to open another command prompt window(Make sure the server command prompt window is also open). now type:
java client 10.69.23.203
Thats it.
if anyone have any problems please post a comment and i will answer all of your questions or if you are having trouble in compiling.

This code illustrates using ruby REXML package. It converts J2EE web application deployment descriptor web.xml into Freemind mindmap document.

This class intended to collect TODO comments from java/c++/etc source files.

Example:

protected readFileData (String path) throws IOException {
// TODO: add try...catch block for IOException
InputStream is = new FileInputStream(path);
...
}


See also DirectoryScanner class.

Configurable number formatter.

Implementation-independent XML builder.

This class uses reflection to locate option setters. Client class must contains methods setFile (to receive file names from the command line) and setOption### (to receive option ###).

(See also adapter-based implementation)

Based on "Random Password Generation"

What is Dijkstra Algorithm? click on the link above and first understand what the algorithm is all about. in short it calculates the shortest path from A to F or vise versa. This code i can guarantee is the simplest and easiest code to understand. just search on google and try to compare this code and other dijkstra code and you will see what i am talking about. i spent alot of time myself and my instructor to guide me on the rite path.
http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm(Description)
to see how the algorithm really works go on this website it tells you step by step how to update the cost and which path to choose.
http://renaud.waldura.com/doc/java/dijkstra/
Please give some time to understand the algorithm first and then you can see my code. if you done understand the algorithm it is very useless. i know alot of people need Dijkstra algorithm in java for their HW assignment or Test. i am giving you the solution step by step. anyone who wants to understand please go to the url i have posted above and once you have understand then run the code and for those people who just want to copy so that they can get 90% in their test No Problem Here it is .
First open a notepad and name that file anything like data.txt or datas.txt and make sure the file looks something like this and in this format.
0 3 100 5 100 100 (100 represents infinity)
3 0 6 7 7 100
100 6 0 5 5 3
5 7 5 0 1 100
100 7 5 1 0 2
100 100 3 100 2 0
i name this file as a data.txt file. i have 6 nodes. and A is always the starting node which has the cost of 0 so by looking at the first line i
know that A to A have distance 0, A to B is 3, A to c is Infinity, A to D is 5, A to E is Infinity(means no edge connected with A), A to F is Infinity.
for second line(B to A is 3, and then vise versa) and for the 3rd line it starts for C and etc..
save the txt file by any name and then copy the code which i have posted and then to run type this:
javac routing.java
java routing data.txt
you will get the output. i will say this one more time understand how the algorithm works or ......................

I was looking for an easy way to populate a combo box with strings taken from an enumeration, and also to be able to pull out Enum objects from the combo box. After some searching, I found EnumComboBoxModel on the JDesktop website, but was not able to find any code.

Instead I came up with an easier solution that did not require me to define a new Model class, but instead uses javax.swing.DefaultComboBoxModel.

Sorry for the disorganization of the code, but hopefully you get the idea.

Two very usefull functions to have around.

(note: dollarfy requires commify to work)

This function returns a Date object being set at 12 A.M. It is useful for comparing dates where you don't know if they'll come set at the beginning of the day or not.

Classe que pren una frase i una clau i obté com a sortida el missatge encriptat usant l'algorisme de Vigenère.

Classe que donada una frase té com a sortida la mateixa frase però havent-li aplicat la xifra del cèsar (per defecte amb valor 3).

PHP function to validate an email address.

I use this function when passing an array to a function being called from setTimeout();

Similar to Perl's CGI::escapeHTML(), though (because we can!) this adds it as a method to all String objects.

Turns any string backwards. If you input "Test" it gives out "tseT". Hope it's useful.

The snippet shows how to use it.

The modus operandi for this is similar to that taken by PHP's implementation of such functions. It's comparitively memory-intensive, but is much faster than running a whole bunch of tests.

Basically, you set a mask -- an array of 256 null bytes -- and set those that correspond to characters you wish to trim. Then, rather than having to test if a character is in the set of characters to trim(O(n), or linear time on *ws), you just test once (O(1), or unit time) to see if the byte in question is set.

And of course, to trim(), you just wrap trim() around both ltrim() and rtrim().

One point of caution: these functions trim in place, so copy strings before trimming them. (Of course, if you usually want access to both pre- and post-trimmed strings, you could always make these malloc() a new string and return a pointer to it . . . )

Generates an 88 character secure hash string for the passed in strings.

A simple tool used for fast Exponentiation. Very useful if you are creating your own cryptograpgic methods.

A simple tool used for fast Exponentiation. Very useful if you are creating your own cryptograpgic methods.

This function loads an File into an String.

This function provides the reverse of a string. It is constructed using string builder because strings in .NET are immutable, while stringbuilders are not. Therefore large strings could be slow to reverse if a regular string was used for the working value that is returned.

This snippet generates a secure hash string using VB.NET

One of best and unknown built in string function included in .NET is String.Split(). It has come in quite handy for my in the last 2 years that I thought I'd share. Pretty basic example here...and for my first post, I thought I'd throw in a little File IO (for free of course)! This was written in .NET 2.0 and it will take little to no modification to make it work in 1.0/1.1.

Simple function to check for a valid email address. Makes sure the @ and a . are in the right place. There is most likely a perl package on CPAN that would be more extensive, but this happens to work for my uses.

This is a quick and easy class that will generate MD5 hashes from strings. I originally wrote it to insert into my Oracle database so I could generate MD5 hases for passwords from PL/SQL.

Example

String md5Hash = stringMD5("my password");

If you only want to compare yyyy-mm-dd you can use the java.sql.Date class, the valueOf method does the trick. It's perfectly safe as the sql Date class is a subclass of the Date class.

Check out the docs here for more detail.

enjoy

Gets a regular expression that'll search for any regexp pattern specified in the parameters.

Gets the rightmost substring, of the specified length, from a String object.

Method for get n random number's

So... this is a simple and great way for validate email address using regular expressions. happy programming!

Sometimes you need to remove slashes from POST variables which could contain arrays. The standard slipslashes-function only takes a string as parameter.

This function removes slashes from both a simple string and array variable.

Generate a random number or string in PHP.

Convert an irregular name=value pair string into a formatted array.

Given a string, you can return an Enum value

Originally found at http://codeproject.com/dotnet/EnumTips.asp?df=100&forumid=38264&exp=0&select=797671

Servlet returning an image.

With Java Web Start 1.5.0 all of a sudden new proxy properties were introduced (deployment.proxy.http.host, deployment.proxy.http.port and deployment.proxy.bypass.list) valid only for the webstart environment - and if that was not enough yet, it does not support the existing proxy properties, neither the standard, nor the deprecated ones from old Java releases. To topple even that, for the bypass-list the delimiters were changed to semicolon (http.nonProxyHosts has the pipe char as delimiter) ...

standard networking properties

the workaround here makes sure, that if any one of these proxy properties (deprecated, standard or webstart-5 ones) are set, that all the others get the same settings - this pays off, if you're using different third-party components relying on one specific set of these proxy properties (especially if it's beyond your power, in what kind of environment the software will be executed respectively integrated...)

if you use the same buildfiles on your local codebase and your continuous integration buildserver, the if-attribute for ant's targets comes in handy...

for this ant buildfile snippet to only create+publish javadoc when executed on the buildserver, the buildserver only has to set the referred system property, e.g. on its startup by using a Java D-option "-Dcontinuous.build=true" ...

ant buildtool website

Java properties files can yield undesirable results at runtime, if there happen to be spaces at the end of some lines.

Requires a win32 port for the GNU utilities grep and sed - e.g. http://unxutils.sourceforge.net/.

Another solution recommends using a text match pattern.
This works, but as long as you've got mail.jar in your classpath anyway, you might as well use this technique instead. (Plus, I think it works with older JDK 1.2+, whereas pattern.compile is 1.4+)

Note that it also accepts a comma-separated list of emails, just like a To: or CC: address line would.

Another way to generate a unique ID.

Retrieve email adresses from a given text file

Reading and writing to a URL connection, thanks to Java.

Here's a nifty trick I often use for testing.

Lets say you have a c:\foo\lib directory full of jarfiles for log4j, javamail...whatever.

Modern J2EE containers do a nice job of letting you deploy a jarfile with your code and have a lib directory full of jarfiles like this, but what if you just want to run a quick client from the command line?

Here's what you do:

Do you find yourself implementing toString on your objects all the time, and wondering why (the debugger seems to do a pretty good job of it all by itself)...well, here's a bit of introspection applied to the problem. This is for all those quick debug sessions where you just want to do System.out.println(myComplexObject).

Instead, just do System.out.println(DebugPrint.toString(myComplexObject));

A handy class I use all the time to encapsulate the idea of whether two events coincide. For example, given a time period representing a shift, and a list of time periods representing transactions or sessions or whatever, find which ones are either totally or partially within the time period. This class make it a bit easier.

Recursively delete a directory, emptying all contents.

This function calculates how many lines will text occupy.
Example (simple):


$string = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Phasellus tincidunt posuere dolor";

$num_lines = how_many_lines(10, $string);

It accepts a third, optional, parameter $options, that allows you to change behaviour. $options should be array. Following configuration options are available:

'white_spaces' - default: array(' ', "\t") - array of chars, that should be treated as whitespace.

'new_lines' - default: array("\r\n", "\n") - array of strings, that should be treated as newlines. For example, for HTML you can set 'new_lines' => array('');

'force_line_breaks' - default: true - force wrapping, when the token is longer than width, or not. If set to false, and token cannot be fitted into $width, function will return false;

'callback' - default: null - callback function for determining character width. Must accept at least one parameter - $char

'callback_params' - default: array() - optional additional callback parameters

'char_widths' - default: null - associative array in a form $char => $width, which contains char width. If $char is not found in the array, it's width is defaulted to 0.