HOW TO FIX THIS ERROR?

moManager.java FXMainPane.java mport java.io.IOException: FXDriver.jave x Crypto Manager Tusjeva Navigator (De... Problems a Javadoc Declaration XX BABE FXDriver (1) (Java Application) /Library/Java/JavavirtualMac Error: Unable to initialize main class FXDriver Caused by: java.lang.NoclassDefFoundError: Stage ublic class FXDriver extends Application ! * The main method for the GUI example program JavaFX version * @param args not used * @throws IOException */ public static void main(String[] args) { Launch(args); } @Override public void start stage stage) throws Exception 1/call the main scene which is a Border Pane FlainPane root = new FxMainPane(); stage.setScene(new Scea (root, 600, 400)); // Set stage title and show the stage. stage.setTitle("Cybersecurity Encryption and Decryption"); stage.show(); }