判定Java源文件名稱

import java.util.Scanner;


public class Main {


public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner cin = new Scanner(System.in);
String s = cin.nextLine();
//StringBuffer stb = new StringBuffer();
while (s != null) {


System.out.println(vital(s));
s = cin.nextLine();
}
}


public static boolean vital(String s) {
int a = s.indexOf('.');
//StringBuilder stb=new StringBuilder(s);
//System.out.println(s.substring(a+1));
String sa=s.substring(a+1);
boolean b=false;
if(sa.equals("java"))
{
b=true;
}
if (Character.isJavaIdentifierStart(s.charAt(0))&& b
&& a != 0) {
for (int i = 1; i < a; i++) {
if (!Character.isJavaIdentifierPart(s.charAt(i))) {
return false;
}
}
return true;
}
return false;
}
}