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Creating Menus

Menu Bar and Menus

The event handling for menus does seem to benefit from the Java 1.1 event model, but Java’s approach to menus is still messy and requires a lot of hand coding. The right medium for a menu seems to be a resource rather than a lot of code. Keep in mind that program-building tools will generally handle the creation of menus for you, so that will reduce the pain somewhat (as long as they will also handle the maintenance!).

In addition, you’ll find the events for menus are inconsistent and can lead to confusion: MenuItems use ActionListeners, but CheckboxMenuItems use ItemListeners. The Menu objects can also support ActionListeners, but that’s not usually helpful. In general, you’ll attach listeners to each MenuItem or CheckboxMenuItem, but the following example (revised from the earlier version) also shows ways to combine the capture of multiple menu components into a single listener class. As you’ll see, it’s probably not worth the hassle to do this.

Here is an example code to create a menu

import javax.swing.*;
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
class fram extends Frame
{
 String msg="";
 CheckboxMenuItem debug,test;
 fram(String str)
  {
   super(str);
   MenuBar mbar=new MenuBar();
   setMenuBar(mbar);
   Menu file= new Menu("File");
   MenuItem mt1,mt2,mt3,mt4,mt5;
   file.add(mt1=new MenuItem("New.."));
   file.add(mt2=new MenuItem("Open.."));
   file.add(mt3=new MenuItem("Close.."));
   file.add(mt4=new MenuItem(".."));
   file.add(mt5=new MenuItem("Exit.."));
   mbar.add(file);
   
   Menu edit=new Menu("Edit");
   MenuItem mt6,mt7,mt8,mt9;
   edit.add(mt6=new MenuItem("cut"));
   edit.add(mt7=new MenuItem("copy"));
   edit.add(mt8=new MenuItem("paste"));
   edit.add(mt9=new MenuItem("--"));   
   Menu sub=new Menu("special");
   MenuItem mt10,mt11,mt12;
   sub.add(mt10=new MenuItem("first"));
   sub.add(mt11=new MenuItem("second"));
   sub.add(mt12=new MenuItem("third"));
   edit.add(sub);
   
  debug=new CheckboxMenuItem("Debug");
  edit.add(debug);
  test=new CheckboxMenuItem("Testing");
  edit.add(test);
  mbar.add(edit);

mymenuHandler handler=new mymenuHandler(this);
 mt1.addActionListener(handler);   
 mt2.addActionListener(handler);
 mt3.addActionListener(handler);
 mt4.addActionListener(handler);
 mt5.addActionListener(handler);
 mt6.addActionListener(handler);
 mt7.addActionListener(handler);
 mt8.addActionListener(handler);
 mt9.addActionListener(handler);
 mt10.addActionListener(handler);
 debug.addItemListener(handler);
 test.addItemListener(handler);

mywindowAdapter adapter= new mywindowAdapter(this);
 addWindowListener(adapter);
}
public void paint(Graphics g)
{
 g.drawString(msg,50,200);
 if(debug.getState())
   g.drawString("Debug is on",10,220);
 else
   g.drawString("Debug is off",10,220);

if(test.getState())
   g.drawString("Testing is on",10,240);
 else
   g.drawString("Testing is off",10,240);

}
}
class mywindowAdapter extends WindowAdapter{
 fram Fram;
 public mywindowAdapter(fram Fram)
{
 this.Fram=Fram;
}
public void windowClosing(WindowEvent we)
{
 Fram.setVisible(false);
 }
 }
class mymenuHandler implements ActionListener, ItemListener{
 fram Fram;
 public mymenuHandler(fram Fram)
 { 
 this.Fram=Fram;
 }
 public void actionPerformed(ActionEvent ae)
 {
  String msg="you selected..";
  String arg=ae.getActionCommand();
 if(arg.equals("New.."))
  { 
  msg+="new";
  fram f1=new fram("frameno1");
    f1.setVisible(true); 
   // f1.setSize(200,200);
 }
 else if(arg.equals("Open.."))
 { 
 msg+="open";
 }
 else if(arg.equals("Close..")) 
 {
  msg+="clsoe";
 }
 Fram.msg=msg;
 Fram.repaint();
}
 public void itemStateChanged(ItemEvent ie)
 {
  Fram.repaint();
  }
}
public class menudemo1 extends Applet{
Frame f,f1;
 public void init()
 {
  f=new fram("menu demo");
 // f1=new fram("frameno1");
  f.setSize(300,300);
  f.setVisible(true);
 }
public void start()
{
 f.setVisible(true);
 f1.setVisible(true);
 }
public void stop()
 {
  f.setVisible(false);
  f1.setVisible(false);
 }
}


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