Compare two Strings without using predefined function

class StringDemo25
{
static int compare(String s1, String s2)
{
int n=s1.length(), m=s2.length(), i=0;
if(m==n)
{
while(i<n && s1.charAt(i) == s2.charAt(i))
i++;
if(i==m)
return 0;
else
return (int) s1.charAt(i)-s2.charAt(i);
}
else
{
if(m>n)
return (int) -s2.charAt(n);
else
return (int) s1.charAt(m);
}
}
public static void main(String... s)
{
System.out.println(compare("India","Indian"));
}
}