Regular Expression:
    
   A regular expression is a special sequence of characters that helps you match or find other strings or sets of strings, using a specialized syntax held in a pattern. They can be used to search, edit, or manipulate text and data.

   It belongs to java.util.regex package in java.

There are 2 factory (Built-in) classe in java.util.regex package
 (a) Pattern
 (b) Matcher

Methods:
(a) matches(): exact match. its similar to equals() method in String
(b) find(): Partial match. its similar to contains() method in String
(c) start(): start position of the search string
(d) end(): end position of the search String
(e) group(): use to display the search values
(f) replaceAll(): replaces all the matches
(g) replaceFirst(): replaces only the first match
(h) split(): used to split the string using delimeters



Assignments:
Q1: the string contains 10 digits account number. Read the account number?
Ex: The account number 1234567890 is a savings account.

Q2: "agumbe received 120 mm of rain". Display this as "agumbe received many mm of rain"

Q3: without using split separate each words from the string?

Q4: "sundaymondaytuesdaywednesdaythursady", Display this as "sunday, monday, tuesday, wednesday, thursady"

Q5: Find number of occurrence character OR string?
