java获取文件名后缀

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

public class filename {       public static void main(String[] args) {         File file = new File("/Users/pankaj/book.txt");         System.out.println("File extension is: " + getFileExtension(file));           file = new File("/Users/pankaj/header.png");         System.out.println("File extension is: " + getFileExtension(file));           file = new File("/Users/pankaj/java.util.txt");         System.out.println("File extension is: " + getFileExtension(file));           file = new File("/Users/pankaj/snow");         System.out.println("File extension is: " + getFileExtension(file));     }       private static String getFileExtension(File file) {         String fileName = file.getName();         if (fileName.lastIndexOf(".") != -1 && fileName.lastIndexOf(".") != 0)             return fileName.substring(fileName.lastIndexOf(".") + 1);         else return " ";     }   }

　　

运行结果：