Regex special characters required

Used Regex

This regex does the validation, you can test it here :

(?=.*[}{,.^?~=+\-_\/*\-+.\|])(?=.*[a-zA-Z])(?=.*[0-9]).{8,}

Remember that you should use double escape where it has the character \ , so in Java code all backslashes must be double, getting \ .

Java application

In the Java code you can validate with String.matches , as I showed below:

public class JavaFiddle
{
   public static void main(String[] args)
   {
     System.out.println("A{123456".matches("(?=.*[}{,.^?~=+\-_\/*\-+.\|])(?=.*[a-zA-Z])(?=.*[0-9]).{8,}")); //exemplo que passa
     System.out.println("ASD1ASDA".matches("(?=.*[}{,.^?~=+\-_\/*\-+.\|])(?=.*[a-zA-Z])(?=.*[0-9]).{8,}")); //exemplo que nao passa (falta caractere especial)
     System.out.println("ASDAS^^?".matches("(?=.*[}{,.^?~=+\-_\/*\-+.\|])(?=.*[a-zA-Z])(?=.*[0-9]).{8,}")); //exemplo que nao passa (falta numero)
     System.out.println("123^8542".matches("(?=.*[}{,.^?~=+\-_\/*\-+.\|])(?=.*[a-zA-Z])(?=.*[0-9]).{8,}")); //exemplo que nao passa (falta letra)
     System.out.println("WWEA^^1".matches("(?=.*[}{,.^?~=+\-_\/*\-+.\|])(?=.*[a-zA-Z])(?=.*[0-9]).{8,}")); //exemplo que nao passa (nao tem minimo de 8 caracteres)
   }
}

This code displays true on the console when it is a valid pattern, and false for invalid patterns. You can test this code in the JavaFiddle as I did too, just copy and paste the code from that answer.

NOTE: As the special characters were not specified, I used the following characters ( ,.^?~=+-_/*\+ ) as valid You can change the characters that enter as special characters in this part of the regex:
(?=.*[}{,.^?~=+\-_\/*\-+.\|]) , just do not remove the part (?= ... ) , as this signals a positive lookahead , which is required to validate that there is at least one of the characters flagged in the group before starting the capture.

Explanation of Regex

• (?=.* ... ) - is a positive lookahead that will ensure that the following character set MUST be in the string for it to be validated.
• [}{,.^?~=+\-_\/*\-+.\|] - This is the set that defines which characters can be captured by positive lookahead .
• (?=.* ... ) - is a positive lookahead that will ensure that the following character set MUST be in the string for it to be validated.
• [a-zA-Z] - This is the set that characterizes any letter character being uppercase or lowercase.
• (?=.* ... ) - is a positive lookahead that will ensure that the following character set MUST be in the string for it to be validated.
• [0-9] - Is the set that characterizes any number between 0 and 9.
• .{8,} - After these validations, a sequence of any character that does not contain line break (flagged by . ) will be captured. And that is a minimum length of 8 characters (signaled by {8,} ), without maximum limit (if you want to set a limit you can put the maximum character number after , ).

EDITED
Thanks to the user @hkotsubo for telling me about my error