Java [RegEx!:]
Java Regular Expression
Overview - Syntax
Regular expression (regex) defines patterns
to recognise strings. Those patterns can be 
anything: a character, a specific string, a 
group of special characters or a combination
of them. We can use Regular expression for
searching, extracting, and modifying text.
This tutorial shows you an overview of
Regular Expression Syntax.

Syntax
1. Characters
To define content of a regex pattern, we use 
many kinds of character classes:

 character  match                                 abbreviation of

            any single character except newline
    .       (we can use m option to match the 
            newline)
   
   \d       a digit                               [0-9]
  
   \D       a non-digit                           [^0-9]
   
   \s       a whitespace character                [ \t\n\x0B\f\r]
   
   \S       a non-whitespace character            [^\s]
   
   \w       a word character                      [a-zA-Z_0-9]
   
   \W       a non-word character                  [^\w]

When using in real Java code, except '.', we 
should double the 'escape' (\\) :

 String pattern = ". \\d \\D \\W \\w \\S \\s";


Example:
1. The pattern "Java SoloLearn provides \\w" will match:

 -> "Java SoloLearn provides Java Tutorial,
    Code Playground, Java Code"

 with the result:
 "Java SoloLearn provides J"


For that reason, Java regex provides another 
basic construct:

2. Quantifiers
Now we can specify the quantity of the 
character which need to be matched. These 
should be placed right after the specified 
character.

 quantifier  description          abbreviation of

   {x}       exactly x times
   
   {x,}      at least x times
   
             at least x but not
   {x,y}
             more than y times
   
    *        0 or more            {0,}
   
    +        1 or more            {1,}
   
    ?        0 or 1               {0,1}

This is how we use them with specified 
characters

 String pattern = "\\d* \\D+ \\W? \\w{3} \\S{3,} \\s{3,8}";



Example:
1. The pattern "Java SoloLearn provides \\w+"
 will match:

 -> "Java SoloLearn provides Java Tutorial,
    Code Playground, Java Code"

with the result:
"Java Sample Approach provides Java"

2. The pattern "Java SoloLearn provides .+"
 will match:

 -> "Java SoloLearn provides Java Tutorial,
    Code Playground, Java Code"

with the same string result:
"Java SoloLearn provides Java Tutorial, Code
Playground, Java Code"

3. The pattern "Java SoloLearn provides .{15}"
 will match:

 -> "Java SoloLearn provides Java Tutorial,
    Code Playground, Java Code"

 with the result:
 "Java Sample Approach provides Java 
 Tutorial, {whitespace}"

3. Meta characters
 meta     match
 char
 
 .        any character

 ^        the beginning of the line
 
 $        the end of the line
 
 [abc]    the letter a or b or c
 
 [abc]    the letter a or b or c,
 [xz]     then v or z
 
 [^abc]   any, except the letter a or b or c
 
 [a-c1-8] the letter between a and c,
          or from 1 to 7
 
 A|Z      A or Z
 
 ()       grouping

Example:
1. The pattern
 String pattern = "(Java Tutorial|SoloLearn|Java Code)"
 will match:

 -> "Java SoloLearn provides Java Tutorial,
    Code Playground, Java Code"

 with the result containing 3 items:
 // Sample Output:
 [SoloLearn, Java Tutorial, Java Code]


2. The pattern
 String pattern = "[a-zA-Z\\s]+";
will match:

 -> "Java SoloLearn provides Java Tutorial,
    Code Playground, Java Code"

 with the result containing 3 items:
 // Sample Output:
 [Java SoloLearn provides Java Tutorial, {whitespace}Code Playground, {whitespace}Java Code]



Regular expressions in Java - Tutorial
Many_languages_use_the_same_concept:


Examples
To_test_your_own_code,_just_use!

Kotlin:_split()_with_RegEx

SplittingText_Reg:[Ex]ample!

RegEx[ample:]_Capitalize_first_letter.js

RegexMatches

[Challenge:]_Tokenizer



JavaScript [RegEx:]

Learn_Regular_Expressions_for_Beginners!

Regular_Expression_in_JavaScript

A_Practical_Guide_to_RegEx_In_JavaScript



     HappyLearning!:) by_@boolean_maybe
Java Regular Expression Overview – Syntax
