Java Basics Regular Expressions

 A regular expression (RE) is a pattern used to search through text.  It either matches the text (or part of it), or fails to match you can easily extract the matching parts, or change them  REs are not easy to use at first they're like a different programming language inside Java  But, REs bring so much power to string manipulation that they are worth the effort.

Regular Expression Example

Regular Expression Pattern & Matcher

Regular Expression Pattern & Matcher

Regular Expression Example

Methods

Methods Naming

Method Declaration

Methods Method Examples A method that add two numbers. A method sort an array from 1 to 10. A method telling even or odd number. A method printing some message. A method reads from file.

Main Method Every program has a main method. Execution of the program is started from main method. If main method is not defined the program will never execute. There are two types of methods Return a value next = keyboard.nextInt(); keyboard is the calling object. Don’t return a value, called void method System.out.println(“Enter data:”); System.out is the calling object

Void Method Example

Method Returning Value Example