Hi everyone I am a newcomer to java . The error Class , interface ,or enum expected keeps pop up all over the place and i can't fix it. Im wondering can evryone help me This is the code PLEASE HELP Code: import javax.swing.JFrame; // import JFrame class import javax.swing.JLabel; // import JLabel class import javax.swing.JPanel; // import JPanel class import java.awt.Font; // import awt Font class import javax.swing.border.Border; // import Border interface import javax.swing.BorderFactory; // import BorderFactory class import javax.swing.JTextField; // import JTextField class import javax.swing.JComboBox; // import JComboBox class import javax.swing.JButton; // import JButton class import javax.swing.JOptionPane; // import JOptionPane class import java.sql.*; // import ALL SQL package classes import java.awt.event.WindowEvent; // import class WindowEvent import java.awt.event.WindowAdapter; //import abstract class WindowAdapter import java.util.List; // import List class import java.util.ArrayList; // import ArrayList class import java.awt.event.ItemListener; // import int. to listen for item events import java.awt.event.ItemEvent; // indicates item selcted/deselected import java.awt.event.ActionListener; // import int. to listen for action events import java.awt.event.ActionEvent; // indicates action event occurred. import java.text.DecimalFormat; // import class DecimalFormat public class RestaurantBillCalculator1 extends JFrame { private Connection myConnection = null; private Statement myStatement = null; private ResultSet myResultSet = null; private Font restaurantJLabelFont = new Font("SansSerif", Font.BOLD, 16); // create a new font for title label private Font restaurantMenuFont = new Font("SansSerif", Font.BOLD, 12); // create a new font for menu labels private List <String> billItems = new ArrayList<String>(); // declare & initialise ArrayList billItems private final static double TAX_RATE = 0.10; // set generous tax rate private final JComboBox tableNumberJComboBox = new JComboBox(); private final JTextField waiterNameJTextField = new JTextField(); private JPanel waiterJPanel = new JPanel(); // JPanel for waiter info. private JPanel menuItemsJPanel = new JPanel(); // JPanel for menu items private JComboBox beverageJComboBox = new JComboBox(); private JComboBox appetizerJComboBox = new JComboBox(); private JComboBox mainCourseJComboBox = new JComboBox(); private JComboBox dessertJComboBox = new JComboBox(); private final JButton saveTableJButton = new JButton("Save Table"); private DecimalFormat myFormat = new DecimalFormat( "0.00" ); // decimal formatting object //** RestaurantBillCaculator constructor, note there is no "no-arg" RestaurantBillCalculator1(String dbDriver, String dbURL) { this.setResizable(false); // user cannot resize JFrame this.setLayout(null); /** set layout manager to null for JFrame so components can be * placed using absolute positioning */ this.addWindowListener( new WindowAdapter() // anonymous inner class { @Override public void windowClosing( WindowEvent event ) { frameWindowClosing( event ); //invoke method } private void frameWindowClosing(WindowEvent event) { } } // end anonymous inner class ); // end addWindowListener /** Establish database driver & handle exceptions*/ try { Class.forName(dbDriver); // call static method of class "Class" // and pass in URL of Database as argument } catch (ClassNotFoundException e) // catch ClassNotFoundException first! { JOptionPane.showMessageDialog(null, "Invalid database driver" + " provided: " + e.getMessage()); // show error message box System.exit(0); } catch (Exception e) // catch general exception { System.err.println("Exception: " + e.getMessage()); // print error } /** Establish connection to database using URL parameter * & handle exceptions*/ try { myConnection = DriverManager.getConnection(dbURL); } catch (SQLException e) // catch SQLException first! { JOptionPane.showMessageDialog(null, "Unable to locate " + "database: " + e.getMessage()); // show error message box System.exit(0); } catch (Exception e) // catch general exception { System.err.println("Exception: " + e.getMessage()); // print error } /** obtain & display meta info about connection - data about data! */ try { DatabaseMetaData meta = myConnection.getMetaData(); // use meta object to obtain metadata about connection System.out.println("Database product type: " + meta.getDatabaseProductName() + " \nDatabase driver name: " + meta.getDriverName()); // print out connection information } catch (SQLException e) { System.err.println("Exception: " + e.getMessage()); // print error } catch (Exception e) // catch general exception { System.err.println("Exception: " + e.getMessage()); // print error } JLabel restaurantJLabel = new JLabel("Restaurant"); // JLabel with title restaurantJLabel.setFont(restaurantJLabelFont); // set JLabel font restaurantJLabel.setBounds(125, 25, 125, 20); // set x,y,width & height this.add(restaurantJLabel); // add JLabel waiterJPanel.setLayout(null); // set no layout manager to JPanel String waiterTitle = "Waiter information"; // title for border Border waiterInfoBorder = BorderFactory. createRaisedBevelBorder(); // create a raised bevel border waiterInfoBorder = BorderFactory.createTitledBorder (waiterInfoBorder, waiterTitle, 1, 2, restaurantMenuFont); // create a titled border waiterJPanel.setBorder(waiterInfoBorder); // set JPanel border waiterJPanel.setBounds(45, 70, 300, 115); // set x,y, width & height JLabel tableNumberJLabel = new JLabel("Table number:"); // new JLabel tableNumberJLabel.setFont(restaurantMenuFont); // set JLabel font tableNumberJLabel.setBounds(30, 35, 125, 20); // set x,y,width & height waiterJPanel.add(tableNumberJLabel); // add JLabel to JPanel tableNumberJComboBox.setBounds(145, 35, 125, 20); // set bounds tableNumberJComboBox.setFont(restaurantMenuFont); // set font waiterJPanel.add(tableNumberJComboBox); // add to JPanel JLabel waiterNameJLabel = new JLabel("Waiter name:"); // new JLabel waiterNameJLabel.setFont(restaurantMenuFont); // set JLabel font waiterNameJLabel.setBounds(30, 75, 125, 20); // set x,y,width & height waiterJPanel.add(waiterNameJLabel); // add JLabel to JPanel waiterNameJTextField.setBounds(145, 75, 125, 20); waiterNameJTextField.setFont(restaurantMenuFont); // set font waiterJPanel.add(waiterNameJTextField); this.add(waiterJPanel); this.add(createMenuItemsJPanel()); // add waiterJPanel to current JFrame /* The following code initializes the first 4 indices of ArrayList * billItems to null, so that these indices can be set later in the * application. Indices are used to ensure a user can select only * ONE item per category. */ billItems.add(0, null); // index 0 is reserved for beverage category billItems.add(1, null); // index 1 is reserved for appetizer category billItems.add(2, null); // index 2 is reserved for main course category billItems.add(3, null); // index 3 is reserved for dessert category } /** This method returns a JPanel object - menuItemsJPanel */ JPanel createMenuItemsJPanel() { menuItemsJPanel.setLayout(null); // set no layout manager to JPanel String menuTitle = "Menu items"; // title for border Border menuItemsBorder = BorderFactory. createRaisedBevelBorder(); // create a raised bevel border menuItemsBorder = BorderFactory.createTitledBorder (menuItemsBorder, menuTitle, 1, 2, restaurantMenuFont); // create a titled border menuItemsJPanel.setBorder(menuItemsBorder); // set JPanel border menuItemsJPanel.setBounds(45, 190, 300, 200); // set x,y, width & height JLabel beverageJLabel = new JLabel("Beverage:"); // new JLabel beverageJLabel.setFont(restaurantMenuFont); // set JLabel font beverageJLabel.setBounds(30, 35, 125, 20); // set x,y,width & height menuItemsJPanel.add(beverageJLabel); // add JLabel to JPanel beverageJComboBox.setBounds(145, 35, 125, 20); // set bounds beverageJComboBox.setFont(restaurantMenuFont); // set font beverageJComboBox.setEnabled(false); // disable by default loadCategory("Beverage", beverageJComboBox); // pass cat. & JCBox ref beverageJComboBox.addItemListener( new ItemListener()); public void itemStateChanged(ItemEvent e) } ); //add Listener to JComboBox using anonymous inner class; { public void itemStateChanged( ItemEvent event )//State change method } } // Determine whether item in box selected if ( event.getStateChange() == ItemEvent.SELECTED ); // beverageJComboBoxItemStateChanged(event); } // end method itemStateChanged } );// end anonymous inner class menuItemsJPanel.add(beverageJComboBox); // add to JPanel JLabel appetizerJLabel = new JLabel("Appetizer:"); // new JLabel appetizerJLabel.setFont(restaurantMenuFont); // set JLabel font appetizerJLabel.setBounds(30, 75, 125, 20); // set x,y,width & height menuItemsJPanel.add(appetizerJLabel); // add JLabel to JPanel appetizerJComboBox.setBounds(145, 35, 125, 20); // set bounds appetizerJComboBox.setFont(restaurantMenuFont); // set font appetizerJComboBox.setEnabled(false); // disable by default loadCategory("Appetizer", appetizerJComboBox); // pass cat. & JCBox ref appetizerJComboBox.addItemListener( new ItemListener() // add Listener to JComboBox using anonymous inner class { public void itemStateChanged( ItemEvent event )//State change method { // Determine whether item in box selected if ( event.getStateChange() == ItemEvent.SELECTED ); // appetizerJComboBoxItemStateChanged(event); } // end method itemStateChanged } );// end anonymous inner class menuItemsJPanel.add(appetizerJComboBox); JLabel mainCourseJLabel = new JLabel("MainCourse:"); // new JLabel mainCourseJLabel.setFont(restaurantMenuFont); // set JLabel font mainCourseJLabel.setBounds(30, 115, 125, 20); // set x,y,width & height menuItemsJPanel.add(mainCourseJLabel); // add JLabel to JPanel mainCourseJComboBox.setBounds(145, 115, 125, 20); // set bounds mainCourseJComboBox.setFont(restaurantMenuFont); // set font mainCourseJComboBox.setEnabled(false); // disable by default loadCategory("MainCourse", mainCourseJComboBox); // pass cat. & JCBox ref mainCourseJComboBox.addItemListener( new ItemListener() // add Listener to JComboBox using anonymous inner class { public void itemStateChanged( ItemEvent event )//State change method { // Determine whether item in box selected if ( event.getStateChange() == ItemEvent.SELECTED ); } // end method itemStateChanged private void ItemStateChanged(ItemEvent event) { } } );// end anonymous inner class menuItemsJPanel.add(dessertJComboBox); // add to JPanel JLabel dessertJLabel = new JLabel("Dessert:"); // new JLabel dessertJLabel.setFont(restaurantMenuFont); // set JLabel font dessertJLabel.setBounds(30, 155, 125, 20); // set x,y,width & height menuItemsJPanel.add(dessertJLabel); // add JLabel to JPanel dessertJComboBox.setBounds(145, 155, 125, 20); // set bounds dessertJComboBox.setFont(restaurantMenuFont); // set font dessertJComboBox.setEnabled(false); // disable by default loadCategory("Dessert", dessertJComboBox); // pass cat. & JCBox ref dessertJComboBox.addItemListener( new ItemListener() // add Listener to JComboBox using anonymous inner class { public void itemStateChanged( ItemEvent event )//State change method { // Determine whether item in box selected if ( event.getStateChange() == ItemEvent.SELECTED ); // dessertJComboBoxItemStateChanged(event); } // end method itemStateChanged } );// end anonymous inner class menuItemsJPanel.add(dessertJComboBox); // add to JPanel return(menuItemsJPanel); // return menuItemsJPanel } /** method that loads categories into respective JComboBoxs it * receives a String and a JComboBox reference (which will point to * the respective JComboBox that invoked the method0 */ void loadCategory(String beverage, JComboBox beverageJComboBox) { try { myStatement = myConnection.createStatement(); // create statement myResultSet = myStatement.executeQuery( "SELECT name FROM Menu " + "WHERE category = '" + beverage+ "' ORDER BY NAME" ); // executeQuery returns values of query while (myResultSet.next()) // loop through myResultSet { beverageJComboBox.addItem(myResultSet.getString("name")); } // end try { catch (SQLException e) { System.err.println(e.getMessage()); // show error message } catch (Exception e) { System.err.println(e.getMessage()); // show error message } void loadCategory (String appetizer, JComboBox appetizerJComboBox) { try { myStatement = myConnection.createStatement(); // create statement myResultSet = myStatement.executeQuery( "SELECT name FROM Menu " + "WHERE category = '" + appetizer + "' ORDER BY NAME" ); //executeQuery returns values of query while (myResultSet.next()) // loop through myResultSet appetizerJComboBox.addItem(myResultSet.getString("name")); } // end try catch (SQLException e) { System.err.println(e.getMessage()); // show error message } catch (Exception e) { System.err.println(e.getMessage()); // show error message } void loadCategory(String mainCourse = null , JComboBox mainCourseJComboBox) { try { myStatement = myConnection.createStatement(); // create statement myResultSet = myStatement.executeQuery( "SELECT name FROM Menu " + "WHERE category = '" + mainCourse + "' ORDER BY NAME" ); // executeQuery returns values of query while (myResultSet.next()) // loop through myResultSet { mainCourseJComboBox.addItem(myResultSet.getString("name")); } } // end try catch (SQLException e) { System.err.println(e.getMessage()); // show error message } catch (Exception e) { System.err.println(e.getMessage()); // show error message } void loadCategory(String dessert, JComboBox dessertJComboBox) { try { myStatement = myConnection.createStatement(); // create statement myResultSet = myStatement.executeQuery( "SELECT name FROM Menu " + "WHERE category = '" + dessert+ "' ORDER BY NAME" ); // executeQuery returns values of query while (myResultSet.next()) // loop through myResultSet { dessertJComboBox.addItem(myResultSet.getString("name")); } } // end try catch (SQLException e) { System.err.println(e.getMessage()); // show error message } catch (Exception e) { System.err.println(e.getMessage()); // show error message } double calculateSubtotal() { double sub = 0.00; double tax = 0.00; double total = 0.00; try { myStatement = myConnection.createStatement(); // create statement for (int i = 0; i <= 3; i++) { myResultSet = myStatement.executeQuery( "SELECT price FROM Menu " + "WHERE name = '" + billItems.get(i) + "'" ); // executeQuery returns values of query, i.e. prices while (myResultSet.next()) // loop through myResultSet { sub += myResultSet.getDouble("price"); // add value to subTotal } } tax = sub*TAX_RATE; // establish tax amount taxJTextField.setText(myFormat.format(tax)); // place tax amount in taxJTextField total = sub + tax; // total up! totalJTextField.setText(myFormat.format(total)); // place total in totalJTextField } // end try catch (SQLException e) { System.err.println(e.getMessage()); // show error message } catch (Exception e) { System.err.println(e.getMessage()); // show error message } finally { try { myResultSet.close(); // close result set } catch (SQLException e) { System.err.println(e.getMessage()); // show error message } catch (Exception e) { System.err.println(e.getMessage()); // show error message } } // end finally return sub; beverageJComboBox.setSelectedIndex(0); // reset JCBox beverageJComboBox.setEnabled(false); // disable JCBox appetizerJComboBox.setSelectedIndex(0); // reset JCBox appetizerJComboBox.setEnabled(false); // disable JCBox mainCourseJComboBox.setSelectedIndex(0); // reset JCBox mainCourseJComboBox.setEnabled(false); // disable JCBox dessertJComboBox.setSelectedIndex(0); // reset JCBox dessertJComboBox.setEnabled(false); // disable JCBox /* reset & enable waiterJPanel components*/ tableNumberJComboBox.setSelectedIndex(0); // reset JCBox tableNumberJComboBox.setEnabled(true); // enable JCBox waiterNameJTextField.setText(""); // clear text waiterNameJTextField.setEnabled(true); // enable JTF } /** override close operation in this method so that I can close * connections & statements when user closes JFrame */ void frameWindowClosing(WindowEvent event) { try //try to close myStatement & myConnection { myStatement.close(); myConnection.close(); } catch(Exception e) { System.err.println(e.getMessage()); // show error } finally { System.exit(0); // exit application } public static void main(String[] args) { String databaseDriver = "sun.jdbc.odbc.JdbcOdbcDriver"; // initialize to use Access DB by default String databaseURL = "jdbc:odbc:JAVA_ACCESS"; // initialize to use Access DB by default if (args.length != 0) // check if arguments passed at command line { if (args.length < 2) // if there are not exactly two args. { System.out.println("Two arguments required " + "for non-Access Database connection. Attempting " + "to connect to Access Database instead..."); // display message } else if (args.length >= 2) // if there are two args. { databaseDriver = args[0]; // databaseDriver = first arg databaseURL = args[1]; // databaseURL = second arg } } RestaurantBillCalculator1 bill = new RestaurantBillCalculator1(databaseDriver, databaseURL); /** new RestaurantBillCalculator instance, pass in null values of * databaseDriver and databaseURL if args.length is 0. * I check these values in the constructor for this class to determine * which DBMS to use */ bill.setTitle("Restaurant Bill Calculator"); // set RestaurantBillCalculator title bill.setSize(400, 615); // set RestaurantBillCalculator title bill.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // exit program on RestaurantBillCalculator close bill.setVisible(true); // show RestaurantBillCalculator } // end of main } // end of class RestaurantBillCalculator
