Java tutorial
import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.InputStream; import java.util.jar.JarOutputStream; import java.util.jar.Pack200; public class Main { public static void main(String[] args) throws Exception { Pack200.Unpacker unpacker = Pack200.newUnpacker(); JarOutputStream out = new JarOutputStream(new FileOutputStream("outName")); InputStream in = new FileInputStream("inName"); // in = new GZIPInputStream(in); unpacker.unpack(in, out); out.close(); } }