(Java) Set a Custom Last-Modified Date in a Gzip File

See more Gzip Examples

This example demonstrates how to use the SetDt method to specify a custom last-modified date and time that will be embedded in a Gzip file.

A CkDateTime object is first initialized with a specific date/time using an RFC 822 formatted string. This date/time is then applied to the Gzip object using SetDt.

When a compression method is called (such as CompressStringToFile), the specified date/time is included in the Gzip metadata. This allows the resulting .gz file to carry a meaningful timestamp rather than using the current system time.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    // This example demonstrates how to set a custom last-modified date/time
    // that will be embedded in a Gzip file.

    CkGzip gzip = new CkGzip();
    CkDateTime dt = new CkDateTime();

    // Set the date/time using a timestamp format (ISO 8601 style):
    dt.SetFromTimestamp("2025-11-15T12:45:26-05:00");

    // Apply the date/time to the Gzip object:
    success = gzip.SetDt(dt);
    if (success == false) {
        System.out.println(gzip.lastErrorText());
        return;
        }

    // Compress a string so the custom date/time is embedded in the .gz:
    String inputStr = "Example text for Gzip compression.";
    success = gzip.CompressStringToFile(inputStr,"utf-8","output.gz");
    if (success == false) {
        System.out.println(gzip.lastErrorText());
        return;
        }

    System.out.println("Gzip file created with custom last-modified date.");
  }
}