这是菜单栏类，如果将其直接放入主类中，它可以工作，但是在它自己的类中却不能，因为没有构造函数，而且我很难做到这一点，我理解构造函数的重要性，但似乎无法理解我的考虑如何将其添加到此类中
public class MenuBar extends mainClass {
JFrame frame = new JFrame("Assingment");
JMenuBar menuBar;
JMenu menu, submenu;
JMenuItem menuItem;
JPopupMenu popup;
{
menuBar = new JMenuBar();
menu = new JMenu("File");
menu.setMnemonic(KeyEvent.VK_A);
menu.getAccessibleContext().setAccessibleDescription("File Menu");
menuBar.add(menu);
menuItem = new JMenuItem("Load");
menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_1, ActionEvent.ALT_MASK));
menu.add(menuItem);
menuItem.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
JFileChooser fileChooser = new JFileChooser();
switch (fileChooser.showOpenDialog(frame)) {
case JFileChooser.APPROVE_OPTION:
break;
}
}
});
menuItem = new JMenuItem("Save", KeyEvent.VK_T);
menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_2, ActionEvent.ALT_MASK));
menuItem.getAccessibleContext().setAccessibleDescription("Save");
menu.add(menuItem);
menuItem = new JMenuItem("Exit",KeyEvent.VK_T);
menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_3, ActionEvent.ALT_MASK));
menuItem.getAccessibleContext().setAccessibleDescription("Exit");
menuItem.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent ae) {
System.exit(0);
}
});
menu.add(menuItem);
menu = new JMenu("Help");
menu.setMnemonic(KeyEvent.VK_N);
menu.getAccessibleContext().setAccessibleDescription("Help Menu");
menuBar.add(menu);
frame.setJMenuBar(menuBar);
frame.setVisible(true);
}
}
头等舱--
@SuppressWarnings("serial")
public class GraphicsPanel extends JPanel {
private final static Color BACKGROUND_COL = Color.DARK_GRAY;
private BufferedImage image;
public void drawLine(Color color, int x1, int y1, int x2, int y2) {
Graphics g = image.getGraphics();
g.setColor(color);
g.drawLine(x1, y1, x2, y2);
}
public void clear() {
Graphics g = image.getGraphics();
g.setColor(BACKGROUND_COL);
g.fillRect(0, 0, image.getWidth(), image.getHeight());
}
@Override
public void paint(Graphics g) {
// render the image on the panel.
g.drawImage(image, 0, 0, null);
}
GraphicsPanel() {
setPreferredSize(new Dimension(500, 300));
image = new BufferedImage(800, 400, BufferedImage.TYPE_INT_RGB);
// Set max size of the panel, so that is matches the max size of the image.
setMaximumSize(new Dimension(image.getWidth(), image.getHeight()));
clear();
}
}
主课--
public class mainClass extends GraphicsPanel {
public static void main(String[] args)
{
JFrame frame = new JFrame ("Assingment");
mainClass GraphPan = new mainClass();
MenuBar mnuBar=new MenuBar();
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
frame.setContentPane(GraphPan);
frame.pack();
frame.setVisible(true);
}
}
最佳答案
public class TestGui extends JFrame {
public TestGui() {
super();
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setResizable(true);
this.getContentPane().setLayout(new BorderLayout());
createMenu(this.getContentPane());
createPanel(this.getContentPane());
this.pack();
this.setPreferredSize(this.getSize());
this.setLocationRelativeTo(null);
}
private void createMenu(Container pane) {
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Datei");
menuBar.add(menu);
JMenuItem menuItemClose = new JMenuItem("Schließen");
JMenuItem menuItemEdit = new JMenuItem("Bearbeiten");
JMenuItem menuItemUndo = new JMenuItem("Rückgängig");
menuItemEdit.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_E, ActionEvent.CTRL_MASK));
menuItemEdit.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
}
});
menuItemClose.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F4, ActionEvent.ALT_MASK));
menuItemClose.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
dispose();
}
});
JMenuItem menuItemAdd = new JMenuItem("Einfügen");
menuItemAdd.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_N, ActionEvent.CTRL_MASK));
menuItemAdd.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
}
});
menuItemUndo.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Z, ActionEvent.CTRL_MASK));
menuItemUndo.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
}
});
menu.add(menuItemAdd);
menu.add(menuItemEdit);
menu.add(menuItemUndo);
menu.add(menuItemClose);
menuBar.setMinimumSize(new Dimension(100, 21));
pane.add(menuBar, BorderLayout.PAGE_START);
}
private void createPanel(Container contentPane) {
JPanel g = new JPanel();
g.setPreferredSize(new Dimension(500, 300));
image = new BufferedImage(800, 400, BufferedImage.TYPE_INT_RGB);
// Set max size of the panel, so that is matches the max size of the
// image.
g.setMaximumSize(new Dimension(image.getWidth(), image.getHeight()));
clear();
add(g);
}
private final static Color BACKGROUND_COL = Color.DARK_GRAY;
private BufferedImage image;
public void drawLine(Color color, int x1, int y1, int x2, int y2) {
Graphics g = image.getGraphics();
g.setColor(color);
g.drawLine(x1, y1, x2, y2);
}
public void clear() {
Graphics g = image.getGraphics();
g.setColor(BACKGROUND_COL);
g.fillRect(0, 0, image.getWidth(), image.getHeight());
}
@Override
public void paint(Graphics g) {
// render the image on the panel.
g.drawImage(image, 0, 0, null);
}
}
此代码将创建一个窗口，其左上角有一个菜单栏和一个深灰色的 jpanel。唯一的问题是菜单栏位于 jpanel 后面，但如果您用类(class)器点击菜单，您就会看到它
关于java - 我需要帮助向此类添加构造函数，以便我可以将菜单栏添加到我的主类，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/40974696/