Salve sono un neofita in java e avrei bisogno di aiuto. Ho copiato il codice che mi permette di avere dei menu in una applicazione J ed inoltre mi permette di fare una linea sul frame attivo. il codice non funziona e mi da come risposta :
java.lang.NoSuchMethodError: main
Exception in thread "main"
Se vi posto il codice npotete aiutarmi a capire che errori ho fatto? Grazie
codice:package components; import java.awt.*; import java.awt.event.*; import javax.swing.JPopupMenu; import javax.swing.JMenu; import javax.swing.JMenuItem; import javax.swing.JCheckBoxMenuItem; import javax.swing.JRadioButtonMenuItem; import javax.swing.ButtonGroup; import javax.swing.JMenuBar; import javax.swing.KeyStroke; import javax.swing.ImageIcon; import java.applet.Applet; import java.awt.*; import java.awt.geom.*; import javax.swing.JPanel; import javax.swing.JTextArea; import javax.swing.JScrollPane; import javax.swing.JFrame; /* PopupMenuDemo.java requires images/middle.gif. */ /* * Like MenuDemo, but with popup menus added. */ public class popupdemo implements ActionListener, ItemListener { private static final paint paint = null; JTextArea output; JScrollPane scrollPane; String newline = "\n"; public JMenuBar createMenuBar() { JMenuBar menuBar; JMenu menu, submenu; JMenuItem menuItem; JRadioButtonMenuItem rbMenuItem; JCheckBoxMenuItem cbMenuItem; //Create the menu bar. menuBar = new JMenuBar(); //Build the first menu. menu = new JMenu("A Menu"); menu.setMnemonic(KeyEvent.VK_A); menu.getAccessibleContext().setAccessibleDescription( "The only menu in this program that has menu items"); menuBar.add(menu); //a group of JMenuItems menuItem = new JMenuItem("A text-only menu item", KeyEvent.VK_T); //menuItem.setMnemonic(KeyEvent.VK_T); //used constructor instead menuItem.setAccelerator(KeyStroke.getKeyStroke( KeyEvent.VK_1, ActionEvent.ALT_MASK)); menuItem.getAccessibleContext().setAccessibleDescription( "This doesn't really do anything"); menuItem.addActionListener(this); menu.add(menuItem); ImageIcon icon = createImageIcon("busy.gif"); menuItem = new JMenuItem("Both text and icon", icon); menuItem.setMnemonic(KeyEvent.VK_B); menuItem.addActionListener(this); menu.add(menuItem); menuItem = new JMenuItem(icon); menuItem.setMnemonic(KeyEvent.VK_D); menuItem.addActionListener(this); menu.add(menuItem); //a group of radio button menu items menu.addSeparator(); ButtonGroup group = new ButtonGroup(); rbMenuItem = new JRadioButtonMenuItem("A radio button menu item"); rbMenuItem.setSelected(true); rbMenuItem.setMnemonic(KeyEvent.VK_R); group.add(rbMenuItem); rbMenuItem.addActionListener(this); menu.add(rbMenuItem); rbMenuItem = new JRadioButtonMenuItem("Another one"); rbMenuItem.setMnemonic(KeyEvent.VK_O); group.add(rbMenuItem); rbMenuItem.addActionListener(this); menu.add(rbMenuItem); //a group of check box menu items menu.addSeparator(); cbMenuItem = new JCheckBoxMenuItem("A check box menu item"); cbMenuItem.setMnemonic(KeyEvent.VK_C); cbMenuItem.addItemListener(this); menu.add(cbMenuItem); cbMenuItem = new JCheckBoxMenuItem("Another one"); cbMenuItem.setMnemonic(KeyEvent.VK_H); cbMenuItem.addItemListener(this); menu.add(cbMenuItem); //a submenu menu.addSeparator(); submenu = new JMenu("A submenu"); submenu.setMnemonic(KeyEvent.VK_S); menuItem = new JMenuItem("An item in the submenu"); menuItem.setAccelerator(KeyStroke.getKeyStroke( KeyEvent.VK_2, ActionEvent.ALT_MASK)); menuItem.addActionListener(this); submenu.add(menuItem); menuItem = new JMenuItem("Another item"); menuItem.addActionListener(this); submenu.add(menuItem); menu.add(submenu); //Build second menu in the menu bar. menu = new JMenu("Another Menu"); menu.setMnemonic(KeyEvent.VK_N); menu.getAccessibleContext().setAccessibleDescription( "This menu does nothing"); menuBar.add(menu); return menuBar; } public Container createContentPane() { //Create the content-pane-to-be. JPanel contentPane = new JPanel(new BorderLayout()); contentPane.setOpaque(true); //Create a scrolled text area. output = new JTextArea(5, 30); output.setEditable(false); scrollPane = new JScrollPane(output); //Add the text area to the content pane. contentPane.add(scrollPane, BorderLayout.CENTER); return contentPane; } public void createPopupMenu() { JMenuItem menuItem; //Create the popup menu. JPopupMenu popup = new JPopupMenu(); menuItem = new JMenuItem("A popup menu item"); menuItem.addActionListener(this); popup.add(menuItem); menuItem = new JMenuItem("Another popup menu item"); menuItem.addActionListener(this); popup.add(menuItem); //Add listener to the text area so the popup menu can come up. MouseListener popupListener = new PopupListener(popup); output.addMouseListener(popupListener); } public void actionPerformed(ActionEvent e) { JMenuItem source = (JMenuItem)(e.getSource()); String s = "Action event detected." + newline + " Event source: " + source.getText() + " (an instance of " + getClassName(source) + ")"; output.append(s + newline); output.setCaretPosition(output.getDocument().getLength()); } public void itemStateChanged(ItemEvent e) { JMenuItem source = (JMenuItem)(e.getSource()); String s = "Item event detected." + newline + " Event source: " + source.getText() + " (an instance of " + getClassName(source) + ")" + newline + " New state: " + ((e.getStateChange() == ItemEvent.SELECTED) ? "selected":"unselected"); output.append(s + newline); output.setCaretPosition(output.getDocument().getLength()); } // Returns just the class name -- no package info. protected String getClassName(Object o) { String classString = o.getClass().getName(); int dotIndex = classString.lastIndexOf("."); return classString.substring(dotIndex+1); } /** Returns an ImageIcon, or null if the path was invalid. */ protected static ImageIcon createImageIcon(String path) { java.net.URL imgURL = popupdemo.class.getResource(path); if (imgURL != null) { return new ImageIcon(imgURL); } else { System.err.println("Couldn't find file: " + path); return null; } } /** * Create the GUI and show it. For thread safety, * this method should be invoked from the * event-dispatching thread. * @param <paint> */ private static <paint> void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("PopupMenuDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create/set menu bar and content pane. popupdemo demo = new popupdemo(); frame.setContentPane(demo.createContentPane()); frame.setJMenuBar(demo.createMenuBar()); paint p new paint; //Create and set up the popup menu. demo.createPopupMenu(); //Display the window. frame.setSize(450, 260); frame.setVisible(true); Graphics2D g2 =(Graphics2D)g; Stroke stroke = newbasicstroke(5.5f); g2.setStroke(stroke); g2.setColor(Color.RED); GeneralPath figura = new GeneralPath; figura.append(new2dfloat(10,10,150,20),false); g2.draw(figura); frame.show(); } //public popupdemo() { //createAndShowGUI(); //} class PopupListener extends MouseAdapter { JPopupMenu popup; PopupListener(JPopupMenu popupMenu) { popup = popupMenu; } public void mousePressed(MouseEvent e) { maybeShowPopup(e); } public void mouseReleased(MouseEvent e) { maybeShowPopup(e); } private void maybeShowPopup(MouseEvent e) { if (e.isPopupTrigger()) { popup.show(e.getComponent(), e.getX(), e.getY()); } } } public void paint(Graphics g, Object color){ Graphics2D g2 =(Graphics2D)g; Stroke stroke = newbasicstroke(5.5f); g2.setStroke(stroke); g2.setColor(Color.RED); GeneralPath figura = new GeneralPath; figura.append(new2dfloat(10,10,150,20),false); g2.draw(figura); }
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