code: public void jarDir(File dirOrFile2Jar, File destJar)
  		throws IOException {
  
  		if (dirOrFile2Jar == null || destJar == null) {
  			throw new IllegalArgumentException();
  		}
  
  		mDestJarName = destJar.getCanonicalPath();
  		FileOutputStream fout = new FileOutputStream(destJar);
  		JarOutputStream jout = new JarOutputStream(fout);
  		//jout.setLevel(0);
  		try {
  			jarDir(dirOrFile2Jar, jout, null);
  		} catch (IOException ioe) {
  			throw ioe;
  		} finally {
  			jout.close();
  			fout.close();
  		}
  	}
docs: Jars a given directory or single file into a JarOutputStream.