Java I/O - 如何显示文本文件的第一行和最后一行

import java.io.BufferedReader;
import java.io.FileReader;

public class Main {
  
  public static void main(String[] args) throws Exception {
    String first, last=null, line;
    BufferedReader in = new BufferedReader(new FileReader(args[0]));
    first = in.readLine();
    while ((line = in.readLine()) != null) {
      if (line != null) {
        last = line;
      }
    }
    System.out.println(first + "\n" + last);
    in.close();
  }
}