using if statment with regular expressions to know if String contains specified characters or not in java

Question

i have made this code and i don't know what is the problem with it, why the output print " f "??? even that the string contains the specified characters in the regex

String s="x^2+x-20"; 
Pattern pattern = 
Pattern.compile("([+-][0-9]*)(([a-z A-Z])\\^2)"); //regex

Matcher matcher = pattern.matcher(s);

if(matcher.matches()){
   System.out.println("t");
} else {
   System.out.println("f");}

score 0 · Accepted Answer · answered Jun 21 '15 at 15:46

Your regex makes [+-] not an optional match but rather required. Use the following:

"([+-]?[0-9]*)(([a-z A-Z])\\^2)" // java syntax

Or as a regex without any java escaping:

([+-]?[0-9]?)(([a-z A-Z])\^2)

Also use Matcher.find rather than Matcher.match to find matches that are not the entire string.

using if statment with regular expressions to know if String contains specified characters or not in java

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