How to create a regex for accepting only alphanumeric characters? [duplicate]

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Regular Expression for alphanumeric and underscores

How to create a regex for accepting only alphanumeric characters?

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Try below Alphanumeric regex

"^[a-zA-Z0-9]*$"

^ - Start of string

[a-zA-Z0-9]* - multiple characters to include

$ - End of string

See more: http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html

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[a-zA-Z0-9] will only match ASCII characters, it won't match

String target = new String("A" + "\u00ea" + "\u00f1" +
                             "\u00fc" + "C");

If you also want to match unicode characters:

String pat = "^[\\p{L}0-9]*$";

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Only ASCII or are other characters allowed too?

^\w*$

restricts (in Java) to ASCII letters/digits und underscore,

^[\pL\pN\p{Pc}]*$

also allows international characters/digits and "connecting punctuation".

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try with \w

http://download.oracle.com/javase/tutorial/essential/regex/pre_char_classes.html

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Use this ^[a-zA-Z0-9_]*$

See here for more info.

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see http://download.oracle.com/javase/1.5.0/docs/api/java/util/regex/Pattern.html

for example [A-Za-z0-9]