Programming: Java - Добро пожаловать в мир Java

Исходный текст приложения MenuApp представлен в листинге 1.

Листинг 1. Файл MenuApp.java

import java.awt.*;

public class MenuApp
{
  public static void 
  main(String args[])
  {
    MainFrameWnd frame = 
      new MainFrameWnd("MenuApp");

    frame.setSize(
    frame.getInsets().left +
      frame.getInsets().right  + 320,
      frame.getInsets().top  +
      frame.getInsets().bottom + 240); 

    frame.show();
  }
}

class MainFrameWnd extends Frame
{
  MenuBar mbMainMenuBar;
  Menu mnFile;
  Menu mnHelp;

  public MainFrameWnd(String sTitle)
  {
    super(sTitle);    

    setSize(400, 200);

    setBackground(Color.yellow);
    setForeground(Color.black);

    setLayout(new FlowLayout());

    mbMainMenuBar = new MenuBar();

    mnFile = new Menu("File");

    mnFile.add("New");
    mnFile.add("-");
    mnFile.add("Exit");

    mnHelp = new Menu("Help"); 

    mnHelp.add("Content");
    mnHelp.add("-");
    mnHelp.add("About");

    mbMainMenuBar.add(mnFile);
    mbMainMenuBar.add(mnHelp);

    setMenuBar(mbMainMenuBar);
  }

  public void paint(Graphics g)
  {
    g.setFont(new Font(
      "Helvetica", Font.PLAIN, 12));

    g.drawString("Frame window", 10, 70);

    super.paint(g);
  }

  public boolean handleEvent(Event evt)
  {
    if(evt.id == Event.WINDOW_DESTROY)
    {
      setVisible(false);
      System.exit(0);
      return true;
    }
    else
      return super.handleEvent(evt);
  }

  public boolean action(Event evt, Object obj)
  {
    MenuItem mnItem;

    if(evt.target instanceof MenuItem)
    {
      mnItem = (MenuItem)evt.target;

      if(obj.equals("Exit"))
      {
        System.exit(0);
      }

      else if(obj.equals("New"))
      {
        MessageBox mbox;

        mbox = new MessageBox(
          "Item New selected",
          this, "Dialog from Frame", true);
        mbox.show();
      }

      else if(obj.equals("Content"))
      {
        MessageBox mbox;

        mbox = new MessageBox(
          "Item Content selected",
          this, "Dialog from Frame", true);
        mbox.show();
      }

      else if(obj.equals("About"))
      {
        MessageBox mbox;
        mbox = new MessageBox(
          "Item About selected",
          this, "Dialog from Frame", true);
        mbox.show();
      }
      else
        return false;
      return true;
    }
    return false;
  }
}

class MessageBox extends Dialog
{
  Label lbMsg;
  Button btnOK;

  public MessageBox(String sMsg, 
    Frame  parent, String  sTitle,
    boolean  modal)
  {
    super(parent, sTitle, modal);
    resize(200, 100);
    setLayout(new GridLayout(2, 1));
    lbMsg = new Label(sMsg, Label.CENTER);
    add(lbMsg);
    btnOK = new Button("OK");
    add(btnOK);
  }

  public boolean handleEvent(Event evt)
  {
    if(evt.id == Event.WINDOW_DESTROY)
    {
      dispose();
      return true;
    }
    else
      return super.handleEvent(evt);
  }

  public boolean action(Event evt, Object obj)
  {
    Button btn;
    if(evt.target instanceof Button)
    {
      btn = (Button)evt.target;

      if(evt.target.equals(btnOK))
      {
        dispose();
      }
      else
        return false;
      return true;
    }
    return false;
  }
}