sorting - Comparing strings with alphanumerics - Java -

i'm implementing java class compares strings alphanumerics. example, "woot", "w00t" returned "w00t", "woot". class implements comparator interface:

class mycomparator implements comparator<charsequence> {      @override     public int compare (charsequence s1, charsequence s2) {         pattern pattern = pattern.compile("(\\d*)(\\d*)");         matcher m1 = pattern.matcher(s1);         matcher m2 = pattern.matcher(s2);          while (m1.find() && m2.find()) {             int nondigitcompare = m1.group(1).compareto(m2.group(1));             if (0 != nondigitcompare) {                 return nondigitcompare;             }              if (m1.group(2).isempty()) {                 return m2.group(2).isempty() ? 0 : -1;              } else if (m2.group(2).isempty()) {                 return 1;              }              biginteger n1 = new biginteger(m1.group(2));              biginteger n2 = new biginteger(m2.group(2));              int numbercompare = n1.compareto(n2);              if (0 != numbercompare) {                 return numbercompare;              }         }         return m1.hitend() && m2.hitend() ? 0 :                m1.hitend()                ? -1 : 1;     }   } 

for cases above code works fine. however, following string[] arguments fails:

string[] arguments = {"p6.py", "p0007.py", "pa", "2016-05-02", "p.py", ".py", "10.20.30.40", "p9", "b"}; 

it outputs "10.20.30.40, 2016-05-02, .py, b, p6.py, p0007.py, p9 ,p.py , pa" instead of ".py, 10.20.30.40, 2016-05-02, b, p.py, p6.py, p007.py, p9, pa".

what's wrong compare method?