The first group can optionally be enclosed with parentheses, and the first two groups can optionally be followed with a choice of three separators (a hyphen, dot, or space). It’s important that the hyphen appears first in this character class, because if it appeared between other characters, it would create a range, as with .The following layout breaks the regular expression into its individual parts, omitting the redundant groups of digits: ^ # Assert position at the beginning of the string. Any quantifier that allows something to be repeated zero times effectively makes that element optional.And of course, the JDK and JRE (Java Development Kit and Java Runtime Environment).In this tutorial we'll create a "hello world" Java servlet.In this tutorial we'll look at what software you need to install to start developing Java-based websites.All the software you need is free; we'll be using the industry-standard Eclipse IDE together with the highly popular Tomcat server.Sun offers the following certifications for Java technologies: Sun's philosophy is that certification is central to the learning process because it provides validation of skill sets for specific job roles.Sun certification also offers a natural progression to support your career goals.
Sun has developed the following learning paths and course lists: In addition to reading the free materials on the Java web site, such as articles, tutorials, and newsletters and Tech Tips, you can sign up for a Career Accelerator Package (CAP) to take the guesswork out of preparing for certification.performs tasks without providing an user interface.They can communicate with other Android components and send notifications to the user.See Recipes 3.5 and 3.15 for help implementing this regular expression with other programming languages. Character classes allow you to match any one out of a set of characters.This regular expression matches three groups of digits. ( # Capture the enclosed match to backreference 1... is another character class, one that allows any one of three separators.