菜单栏，颜色和图像未添加到框架

Question

我正在尝试添加一个菜单栏，通过对象创建调用其他类，以及尝试将图像添加到帧中。

代码确实可以编译，但我在代码中放置的组件似乎都没有出现？

 import java.awt.*;
 import java.awt.event.*;
 import javax.swing.*;
 import java.text.*;
 import javax.swing.border.*;

  public class Operation 
     extends JFrame implements ActionListener 
  {
      String op="",pre="";

      JFrame calFrame = new JFrame("Calculator");

      JMenuBar mainBar = new JMenuBar();

     JMenu homeMenu = new JMenu("Home");
        JMenuItem welcomeScreen = new JMenuItem("Welcome Screen");
        JMenuItem listHome = new JMenuItem("List Accessories");
     JMenu jumpMenu = new JMenu("Jump To");
         JMenuItem jtSclingTool = new JMenuItem("Scaling Tool");
         JMenuItem jtMetricConv = new JMenuItem("Metric Converter");
     JMenu helpMenu = new JMenu("Help");
        JMenuItem helpScreen = new JMenuItem("Help Screen");
     JMenu exitMenu = new JMenu("Exit");
        JMenuItem exitToHome = new JMenuItem("Exit to Welcome Screen");
        JMenuItem exitProgram= new JMenuItem("Exit Program");

 public void Calculator()
 {
     calFrame.setBounds(0,0,1920,1080);

     calFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     calFrame.setLayout(null);

     JTextField txtid = new JTextField();
     txtid.setBounds(20,20,400,100);
     calFrame.add(txtid);
     txtid.setFont(new java.awt.Font("Lucida Grande", 0, 19));
     txtid.setHorizontalAlignment(javax.swing.JTextField.RIGHT);
     txtid.setText("0");
     txtid.setEnabled(false);

     mainBar.add(homeMenu);
     mainBar.add(jumpMenu);
     mainBar.add(helpMenu);
     mainBar.add(exitMenu);

     homeMenu.add(welcomeScreen);
     homeMenu.add(listHome);
     jumpMenu.add(jtSclingTool);
     jumpMenu.add(jtMetricConv);
     helpMenu.add(helpScreen);
     exitMenu.add(exitToHome);
     exitMenu.add(exitProgram);

     welcomeScreen.addActionListener(this);
     listHome.addActionListener(this);
     helpScreen.addActionListener(this);
     exitToHome.addActionListener(this);
     exitProgram.addActionListener(this);
     jtSclingTool.addActionListener(this);
     jtMetricConv.addActionListener(this);

     JButton a = new JButton ("1");
     a.setBounds(20,440,100,100);
     calFrame.add(a);

     JButton b = new JButton ("2");
     b.setBounds(120,440,100,100);
     calFrame.add(b);

     JButton c = new JButton ("3");
     c.setBounds(220,440,100,100);
     calFrame.add(c);

     JButton d = new JButton ("4");
     d.setBounds(20,340,100,100);
     calFrame.add(d);

     JButton e = new JButton ("5");
     e.setBounds(120,340,100,100);
     calFrame.add(e);

     JButton f = new JButton ("6");
     f.setBounds(220,340,100,100);
     calFrame.add(f);

     JButton g = new JButton ("7");
     g.setBounds(20,240,100,100);
     calFrame.add(g);

     JButton h = new JButton ("8");
     h.setBounds(120,240,100,100);
     calFrame.add(h);

     JButton i = new JButton ("9");
     i.setBounds(220,240,100,100);
     calFrame.add(i);

     JButton j = new JButton ("0");
     j.setBounds(120,540,100,100);
     calFrame.add(j);

     JButton k = new JButton ("+");
     k.setBounds(320,240,100,200);
     calFrame.add(k);

     JButton l = new JButton ("-");
     l.setBounds(320,140,100,100);
     calFrame.add(l);
     //
     JButton m = new JButton ("*");
     m.setBounds(220,140,100,100);
     calFrame.add(m);

     JButton n = new JButton ("/");
     n.setBounds(120,140,100,100);
     calFrame.add(n);

     JButton o = new JButton ("=");
     o.setBounds(320,440,100,200);
     calFrame.add(o);

     JButton p = new JButton (".");
     p.setBounds(220,540,100,100);
     calFrame.add(p);

     JButton q = new JButton ("Del");
     q.setBounds(20,540,100,100);
     calFrame.add(q);

     JButton r = new JButton ("AC");
     r.setBounds(20,140,100,100);
     calFrame.add(r);

     calFrame.setVisible(true);
 }

     public void actionPerformed(ActionEvent e) 
    {
     a.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         if(op.equals("="))
         {
             txtid.setText("1");
             op="";
         }
         else if(txtid.getText().equals("0"))
            txtid.setText("1");
         else
             txtid.setText(txtid.getText()+"1");
        }
     });

     b.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         if(op.equals("="))
         {
             txtid.setText("2");
             op="";
         }
         else if(txtid.getText().equals("0"))
            txtid.setText("2");
         else
             txtid.setText(txtid.getText()+"2");
        }
     });

     c.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         if(op.equals("="))
         {
             txtid.setText("3");
             op="";
         }
         else if(txtid.getText().equals("0"))
            txtid.setText("3");
         else
             txtid.setText(txtid.getText()+"3");
        }
     });

     d.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         if(op.equals("="))
         {
             txtid.setText("4");
             op="";
         }
         else if(txtid.getText().equals("0"))
            txtid.setText("4");
         else
             txtid.setText(txtid.getText()+"4");
        }
     });

     e.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         if(op.equals("="))
         {
             txtid.setText("5");
             op="";
         }
         else if(txtid.getText().equals("0"))
            txtid.setText("5");
         else
             txtid.setText(txtid.getText()+"5");
        }
     });

     f.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
        if(op.equals("="))
        {
             txtid.setText("6");
             op="";
         }
        else if(txtid.getText().equals("0"))
            txtid.setText("6");
         else
             txtid.setText(txtid.getText()+"6");
        }
     });

     g.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae){
         if(op.equals("="))
         {
             txtid.setText("7");
             op="";
         }
         else if(txtid.getText().equals("0"))
            txtid.setText("7");
         else
             txtid.setText(txtid.getText()+"7");
        }
     });

     h.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         if(op.equals("="))
         {
             txtid.setText("8");
             op="";
         }
         else if(txtid.getText().equals("0"))
            txtid.setText("8");
         else
             txtid.setText(txtid.getText()+"8");
        }
     });

     i.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         if(op.equals("="))
         {
             txtid.setText("9");
             op="";
         }
         else if(txtid.getText().equals("0"))
            txtid.setText("9");
         else
             txtid.setText(txtid.getText()+"9");
        }
     });


     j.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         if(op.equals("="))
         {
             txtid.setText("0");
             op="";
         }
         else if(txtid.getText().equals("0"))
            txtid.setText("0");
         else
             txtid.setText(txtid.getText()+"0");
        }
     });

     k.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         op="+";
         pre=txtid.getText();
         txtid.setText("");
        }
     });

     l.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         op="-";
         pre=txtid.getText();
         txtid.setText("");
        }
     });

     m.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         op="*";
         pre=txtid.getText();
         txtid.setText("");
        }
     });

     n.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         op="/";
         pre=txtid.getText();
         txtid.setText("");
        }
     });

      p.addActionListener(new ActionListener()
          {
     public void actionPerformed (ActionEvent ae)
     {
         if(op.equals("="))
         {
             txtid.setText("0.");
             op="";
         }
         else
             txtid.setText(txtid.getText()+".");
     }
     });

     q.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         op="del";
         String str=txtid.getText();
         int p = str.length();
         if(p-1!=0)
             txtid.setText(txtid.getText().substring(0,p-1));
         else
             txtid.setText("0");
        }
     });

     r.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {
         op="";  //AC
         pre=""; //AC
         txtid.setText("0");

        }
     });

     o.addActionListener(new ActionListener()
         {
     public void actionPerformed (ActionEvent ae)
     {       
         switch(op)
         {
             case "":
                 txtid.setText("0");
                 break;
             case "+":
                 txtid.setText((Float.parseFloat(pre)+Float.parseFloat(txtid.getText()))+"");
                 break;
             case "-":
                 txtid.setText((Float.parseFloat(pre)-Float.parseFloat(txtid.getText()))+"");
                 break;
             case "*":
                 txtid.setText((Float.parseFloat(pre)*Float.parseFloat(txtid.getText()))+"");
                 break;
             case "/":
                 txtid.setText((Float.parseFloat(pre)/Float.parseFloat(txtid.getText()))+"");
                 break;
             case "=":
                 break;
             }
             op="=";
         }
     });

        String buttonCommand = e.getActionCommand();
        AlgebraAccessories mainWindow = new AlgebraAccessories();
        ListAccessories listAccessories = new ListAccessories();
        Scaling sclTool = new Scaling();
        MetricConverter mtrConv = new MetricConverter();

        if (buttonCommand.equals("Welcome Screen"))
        {
            calFrame.dispose();
            mainWindow.MainWelcomeWindow();
        }
        else if (buttonCommand.equals("List Accessories"))
        {
            calFrame.dispose();
            listAccessories.selectionWindow();
        }
        else if (buttonCommand.equals("Scaling Tool"))
        {
            calFrame.dispose();
            sclTool.Scale();
        }
        else if (buttonCommand.equals("Metric Converter"))
        {
            calFrame.dispose();
            mtrConv.MetricConverter();
        }
        else if (buttonCommand.equals("Help"))
        {
            calFrame.dispose();
            mainWindow.MainWelcomeWindow();
        }
        else if (buttonCommand.equals("Exit to Welcome Screen"))
        {
            calFrame.dispose();
            mainWindow.MainWelcomeWindow();
        }
        else if (buttonCommand.equals("Exit Program"))
        {
            System.exit(0);
        }
    }

 public static void main(String[] args)
{
    Operation mainGui = new Operation();
    mainGui.Calculator();
}
}