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I had this regex in java that matched either an alphanumeric character or the tilde (~)
^([a-z0-9])+|~$
Now I have to add also the characters - and _ I've tried a few combinations, neither of which work, for example:
^([a-zA-Z0-9_-])+|~$
^([a-zA-Z0-9]|-|_)+|~$
Sample input strings that must match:
woZOQNVddd
00000
ncnW0mL14-
dEowBO_Eu7
7MyG4XqFz-
A8ft-y6hDu ~
Any clues / suggestion?
313
If you have a character you'll first need to convert it to a string before you can use a regular expression: if (Character. toString(symbol). matches("[A-Z?]")) { // ... }
Match any specific character in a setUse square brackets [] to match any characters in a set. Use \w to match any single alphanumeric character: 0-9 , a-z , A-Z , and _ (underscore). Use \d to match any single digit. Use \s to match any single whitespace character.
Notice that the regular expression String contains two backslashes after each other, and then a . . The reason is, that first the Java compiler interprets the two \\ characters as an escaped Java String character. After the Java compiler is done, only one \ is left, as \\ means the character \ .
Regular Expressions or Regex (in short) in Java is an API for defining String patterns that can be used for searching, manipulating, and editing a string in Java. Email validation and passwords are a few areas of strings where Regex is widely used to define the constraints. Regular Expressions are provided under java.
- is a special character within square brackets. It indicates a range. If it's not at either end of the regex it needs to be escaped by putting a \ before it.
It's worth pointing out a shortcut: \w is equivalent to [0-9a-zA-Z_] so I think this is more readable:
^([\w-]+|~$
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