1import java.io.*;
2public class CopyFile {
3
4   public static void main(String args[]) throws IOException {  
5      FileInputStream in = null;
6      FileOutputStream out = null;
7
8      try {
9         in = new FileInputStream("input.txt");
10         out = new FileOutputStream("output.txt");
11         
12         int c;
13         while ((c = in.read()) != -1) {
14            out.write(c);
15         }
16      }finally {
17         if (in != null) {
18            in.close();
19         }
20         if (out != null) {
21            out.close();
22         }
23      }
24   }
25}

1Arrays.asList("a1", "a2", "a3")
2    .stream()
3    .findFirst()
4    .ifPresent(System.out::println);  // a1
5