Representation and basic application of regular expressions

1.[abc]：a、b、c Any character in
2.[^abc]： except a、b、c Any character of
3.[a-z]：a、b、c …、z Any character in
4.[a-zA-Z0-9]：a~ z、A~ Z、0~9 Any character in
5.[a-z&&[^bc]]：a~z In addition to b and c Any character other than , among && Express “ And ” The relationship between
6. •： Any character
7.\d： Any number character , amount to [0-9]
8.\w： Word characters are equivalent to [a-zA-Z0-9_]
9.\s： Blank character 、 amount to [\t\n\x0B\f\r]
10.\D： Non empty numeric character
11.\W： Nonword character
12.\S： Nonwhite space character
13.X?： Express 0 Or 1 individual X
14.X*： Express 0 One or any number of X
16.X{n}： Express n individual X
17.X{n,}： Express n One to any number X（ Greater than or equal to n individual X）
18.X{n,m}： Express n A to m individual X
19.\d+： Integers
20.\d+.\d+： decimal

21. Regular expression of cell phone number :

String supported regular expression method 1 :

• boolean matches(String regex)

• Use the given regular expression to verify the format of the current string , Match returns true

• notes : Whether or not a given regular expression adds a boundary match "$" They all do full match verification

   // String email = "[email protected].cn";
   String email = "[email protected]";
   /*
       email Regular expression of 
       [a-zA-Z0-9_][email protected][a-zA-Z0-9]+(\.[a-zA-Z]+)+
   */
   String regex = "[a-zA-Z0-9_][email protected][a-zA-Z0-9]+(\\.[a-zA-Z]+)+";
   boolean match = email.matches(regex);
   if(match){
       System.out.println(" It's the mailbox ");
   }else{
       System.out.println(" Not a mailbox ");
   }
  

String The second method of regular expression supported :

• String[] split(String regex)

• Split the current string according to the part that satisfies the regular expression , And divide the split part into a String Array form returns

   String str = "567abc123def456ghi789";
   String[] arr = str.split("[0-9]+");
   System.out.println(Arrays.toString(arr));
  

String supported regular expression method 3 :

• String replaceAll(String regex,String str)

• Replace the part of the current string that satisfies the regular expression with the given content

   String str = "abc123def456ghi789klm";
   // Convert digital part to #NUMBER#
   str = str.replaceAll("[0-9]+","#NUMBER#");
   System.out.println(str);