How to compress a file in GZIP format using java?

Question:

How to compress a file in GZIP format?

Code:

import java.io.*;
import java.util.zip.GZIPOutputStream;
 
public class GZipFile {
  public static void main( String[] args ) {
 
    String input = "/tmp/file.txt";
    String output = "/tmp/file.txt.gz";
 
    byte[] buffer = new byte[1024];
 
    try {
 
      FileInputStream in = new FileInputStream(input);
 
      FileOutputStream fos = new FileOutputStream(output);
      GZIPOutputStream gzos = new GZIPOutputStream(fos);
 
      int len;
      while ((len = in.read(buffer)) > 0) {
        gzos.write(buffer, 0, len);
      }
      in.close();
      gzos.finish();
      gzos.close();
      System.out.println("Done");
 
    } catch(Exception ex) {
      System.out.println(ex);
    }
  }
}

Output:

$ java GZipFile
Done

$ ls -l /tmp/file.txt
-rw-rw-r-- 1 dennis dennis 4880 Feb 26 16:42 /tmp/file.txt

$ ls -l /tmp/file.txt.gz
-rw-rw-r-- 1 dennis dennis 56 Feb 26 16:44 /tmp/file.txt.gz