从另一个类调用 JMenuBar

Question

我有以下带有按钮的GUI代码和JMenuBar的代码。

菜单栏测试.java

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import MenuBar.*;
public class MenuBarTest extends JFrame implements ActionListener
{
    JFrame myMainWindow = new JFrame("This is my title");
    JPanel  firstPanel = new JPanel();
    JButton btnTest = new JButton("Refresh Results");
    GuiDMenuBar mbr;
    public void runGUI()
    {
        myMainWindow.setBounds(10, 10, 800, 800);
        myMainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        myMainWindow.setLayout(new GridLayout(1,1));
        createFirstPanel();
        myMainWindow.getContentPane().add(firstPanel);
        myMainWindow.setJMenuBar(mbr.GuiDMenuBar());
        myMainWindow.setVisible(true);
    }
    public void createFirstPanel()
    {
        firstPanel.setLayout(null);
        btnTest.setBounds(100, 100, 200, 50);
        btnTest.addActionListener(this);
        firstPanel.add(btnTest);
    }
    public void actionPerformed(ActionEvent e)
    {
        if(e.getSource() == btnTest)
        {
            System.out.println("Hi");
        }
    }
    public static void main(String[] args)
    {
        MenuBarTest mBT = new MenuBarTest();
        mBT.runGUI();
    }
}

GuiDMenuBar.java

package MenuBar;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;
public class GuiDMenuBar extends JMenuBar
{   
    JMenu m_PopUps;
    public JCheckBoxMenuItem m_p_AllPopUps,m_p_NamePopUps,m_p_TextPopUps,m_p_SizePopUps,m_p_ToolTipPopUps;
    public GuiDMenuBar()
    {
        setBorderPainted(true);
        makePopUpMenu();
    }
    void makePopUpMenu()
    {
        m_PopUps = new JMenu("Pop Ups");
        m_PopUps.setMnemonic('P');
        m_p_AllPopUps = new JCheckBoxMenuItem("Enable All Pop Ups");
        m_p_NamePopUps = new JCheckBoxMenuItem("Enable Name Pop Ups");
        m_p_SizePopUps = new JCheckBoxMenuItem("Enable Automatic Sizing Pop Ups");
        m_p_TextPopUps = new JCheckBoxMenuItem("Enable Add Contents Pop Ups");
        m_p_ToolTipPopUps = new JCheckBoxMenuItem("Enable Add ToolTips Pop Ups");
        m_p_AllPopUps.addItemListener(new ItemListener() 
        {
            public void itemStateChanged(ItemEvent e) 
            {
                if(m_p_AllPopUps.getState())
                {
                    m_p_NamePopUps.setState(true);
                    m_p_SizePopUps.setState(true);
                    m_p_TextPopUps.setState(true);
                    m_p_ToolTipPopUps.setState(true);
                }
                else
                {
                    m_p_NamePopUps.setState(false);
                    m_p_SizePopUps.setState(false);
                    m_p_TextPopUps.setState(false);
                    m_p_ToolTipPopUps.setState(false);
                }
            }
        });
        m_PopUps.add(m_p_AllPopUps);
        m_PopUps.addSeparator();
        m_PopUps.add(m_p_NamePopUps);
        m_PopUps.add(m_p_SizePopUps);
        m_PopUps.add(m_p_TextPopUps);
        m_PopUps.add(m_p_ToolTipPopUps);
        add(m_PopUps);
    }
    public void checkState()
    {
        System.out.println(m_p_AllPopUps.getState());
        System.out.println(m_p_NamePopUps.getState());
        System.out.println(m_p_SizePopUps.getState());
        System.out.println(m_p_TextPopUps.getState());
        System.out.println(m_p_ToolTipPopUps.getState());
    }
}

我的目标是将JMenuBar添加到JFrame中。但是当我编译时，我收到一个错误，说它找不到GuiDMenuBar()。我将非常感谢任何帮助。谢谢

Answer 1

您尝试调用构造函数，就好像它是静态方法一样。不要。而是通过将构造函数作为构造函数调用来创建实例，将实例分配给变量，然后使用它。变化：

// GuiDMenuBar mbr;
GuiDMenuBar mbr = new GuiDMenuBar(); // create instance and assign
public void runGUI()
{
    // ....
    // myMainWindow.setJMenuBar(mbr.GuiDMenuBar());
    myMainWindow.setJMenuBar(mbr); // use instance
    myMainWindow.setVisible(true);
}

接下来我们将讨论null布局和setBounds(...)的弊