Smartly load your properties

Method	Parameter format	Lookup failure behavior	Usage example
ClassLoader. getResourceAsStream()	"/"-separated names; no leading "/" (all names are absolute)	Silent (returns null)	this.getClass().getClassLoader() .getResourceAsStream ("some/pkg/resource.properties")
Class. getResourceAsStream()	"/"-separated names; leading "/" indicates absolute names; all other names are relative to the class's package	Silent (returns null)	this.getClass() .getResourceAsStream ("resource.properties")
ResourceBundle. getBundle()	"."-separated names; all names are absolute; .properties suffix is implied	Throws unchecked java.util.MissingResourceException	ResourceBundle.getBundle ("some.pkg.resource")

and there're more tips in the linked resource below.

Resources

1. Smartly load your properties
   

Difference Between ResourceBundle and Properties Classes in Java

GMHK wrote:
> Can anyone tell me the whats the difference between the resource bundle
> and Properties classes in java.
> As both uses the .properties file to get the string constants.

No, they don't necessarily. A resource bundly does not have to be
file-based. The common implementation, however is. And that common
implementation (PropertyResourceBundle) indeed uses properties files and
thr Properties class.

However, resource bundles also come with a particular lookup-schema to
select a particular bundle according to the Locale. Something which you
don't get with Properties, but which is important when you do some
actual localization.

> At what point of time would the programmer decide to choose which of
> the either classes.

A resource bundle (properties file based or otherwise) when in need for
the lookup of locale-specific data. A naked properties file when in need
for keeping some small (FSWO) set of data persistent (e.g. application
configuration data), which is not supposed to be translated.

You didn't mention Preferences. I still preferen Properties over
Preferences because of the easy-to-work-with text file format, but they
can be used for the same purpose as Properties, without the need of
having to deal with files.

> What i understood so far is resourcebundle makes uses of String manager
> to get the string.
> where as the Properties tries to read the properties directly.

Both map keys to values. The biggest difference is how they get that
mapping. ResourceBundles follow a build-in lookup schema taking a locale
into account. Properties need to be provided with some InputStream,
which the programmer has to handle explicitely. Properties have an easy
way to be written to an OutputStream, while ResourceBundles are ment to
be read-only.

/Thomas

Resources

1. Difference Between ResourceBundle and Properties Classes in Java
   

Multiple Eclipse Installation Management

Resources

1. Managing plugins in eclipse.
2. Eclipse: Managing Multiple Eclipse Installation.
3. Setting up eclipse for painless upgrades.
   

Regular expression and CharSequence in Java

Introduction
Regular expression, specified as a string, is first compiled into an instance of Pattern. The regular expression constructs supported by Pattern are almost the same (see comparison to Perl 5 in javadoc of class pattern) as that supported by Perl 5. The Pattern engine performs traditional NFA-based (Nondeterministic Finite Automate) matching with ordered alternation as occurs in Perl 5.

The regex Package
Two major class Pattern and Matcher, both of which have non-public constructor which means  the client can't new instances of them directly. A Pattern instance is the compiled intermediate representation, plus some helper methods, of the string form regular expression. Instances of Pattern are immutable which means they're thread-safe. And each instance of Matcher, produced by factory method of Pattern, corresponds to each matching between the bound regular expression of the target string ( i.e., the string to be matched). Further information about how to use this package in a program can be found in the resources section.

regex matching in CharSequence
Despite being as part of the java library, the regex package is also used by other parts of the library. These usages are listed below:
boolean String.matches( String regex );
String String.replaceAll( String regex, String replacement )
String String.replaceFirst( String regex, String replacement )
String[] split( String regex )

Note that rather than class String or some other concrete representation of CharSequence, interface CharSequence is widely depended upon both in Pattern and String. Classes implementing CharSequence mainly include String, StringBuffer and StringBuilder. And the implemented methods include such methods that we usually use with String as charAt(int), length(), and subSequence(int, int).


Resources

1. Interface java.lang.CharSequence
2. Package java.util.regex
3. Lesson: Regular Expressions
   

Tips of Using Escape Characters

First, what is the differences between '\n' and '\r\n'?

Cite here: )

It goes back to mechanical teletypes; if you issued a line feed followed by carriage return you got a few characters printed backwards in a diagonal stripe because there was insufficient time for the carriage to move back to the left before it started printing. To overcome this, the carriage return is issued first to give the carriage enough time to return, whilst line feeding, before printing started. It has stuck as a standard ever since.

 
and here:

Different Operating Systems handle newlines in a different way. Here is a short list of the most common ones:

• DOS and Windows
  
  They expect a newline to be the combination of two characters, namely '\r\n' (or 13 followed by 10).
  
  
• Unix (and hence Linux as well)
  
  Unix uses a single '\n' to indicate a new line.
  
  
• Mac
  
  Macs use a single '\r'.

When string are read from user input, escape character can't be explicitly input. For example, in case which string are read from the command line argument, when the user give argument "hello\nworld", the string read in and stored will be "hello\\nworld". This is because escape characters usually are parsed as format presentation rather than literal  occurrence (actually, this is the "unescapted" meaning). For the same reason, in the programming codes escape characters, the literal form of format presentation, are used instead of draw a format presentation that the compiler could understand, which is obviously of non-sense.

Note that using escape characters to specify the format presentation is not the definition of escape character, though in many cases they're used in this way.