Code:
try {

						if ((new File("c:\\OFFER_LETTER_1.pdf")).exists()) {

							Process p = Runtime
									.getRuntime()
									.exec("rundll32 url.dll,FileProtocolHandler c:\\OFFER_LETTER_1.pdf");
							p.waitFor();

						} else {

							System.out.println("File is not exists");

						}

						System.out.println("Done");
...