hi guys,i made the following program:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.IOException;
public class ColorMenu extends QuittableFrame {
public static void main(
String[] args) {
new ColorMenu();
}
public static String msgs = "";
private String[] colorNames =
{ "Black", "White",
"Light Gray", "Medium Gray", "Dark Gray" };
private Color[] colorValues =
{ Color.black, Color.white,
Color.lightGray, Color.gray, Color.darkGray };
public ColorMenu() {
super("gaurav");
MenuBar mbar = new MenuBar();
//Menu colorMenu = new Menu("Colors");
//for(int i=0; i<2; i++)
//colorMenu.add(colorNames[i]);
//Menu grayMenu = new Menu("Gray");
//for(int i=2; i<colorNames.length; i++)>
//grayMenu.add(colorNames[i]);
//colorMenu.add(grayMenu);
//bar.add(colorMenu);
setMenuBar(mbar);
Menu io = new Menu("I/O");
MenuItem item1,item2;
io.add(item1 = new MenuItem("Open network
applet from server"));
io.add(item2 = new MenuItem("-"));
Menu sub = new Menu("Load");
MenuItem item3,item4,item5,item6;
sub.add(item3 = new MenuItem("Node File"));
sub.add(item4 = new MenuItem("Link File"));
sub.add(item5 = new MenuItem("Incident File"));
sub.add(item6 = new MenuItem("TFRU File"));
io.add(sub);
mbar.add(io);
Menu ana = new Menu("Results");
MenuItem item7;
ana.add(item7 = new MenuItem("Analysis"));
mbar.add(ana);
Menu hel = new Menu("Help");
Menu man = new Menu("User Manual");
MenuItem item8,item9,item10;
man.add(item8 = new MenuItem("
Word File"));
man.add(item9 = new MenuItem("Pdf File"));
man.add(item10 = new MenuItem("HTML File"));
hel.add(man);
mbar.add(hel);
MyMenuHandler handler = new MyMenuHandler();
item1.addActionListener(handler);
item2.addActionListener(handler);
item3.addActionListener(handler);
item4.addActionListener(handler);
item5.addActionListener(handler);
item6.addActionListener(handler);
item7.addActionListener(handler);
item8.addActionListener(handler);
item9.addActionListener(handler);
item10.addActionListener(handler);
MyWindowAdapter adapter = new MyWindowAdapter(this);
addWindowListener(adapter);
setBackground(Color.white);
resize(500, 500);
show();
}
public void paint(Graphics g) {
g.setColor(Color.black);
g.drawString(msgs,10,200);
}
}
class MyWindowAdapter extends WindowAdapter {
ColorMenu colorMenu;
public MyWindowAdapter(ColorMenu colorMenu) {
this.colorMenu = colorMenu;
}
public void windowClosing(WindowEvent we) {
colorMenu.setVisible(false);
}
}
class MyMenuHandler implements ActionListener,ItemListener {
ColorMenu colorMenu;
public void MyMenuhandler(ColorMenu colorMenu) {
this.colorMenu = colorMenu;
}
public void actionPerformed(ActionEvent ae) {
String msg = "You selected : ";
System.out.println(msg);
String arg = (String)ae.getActionCommand();
System.out.println(arg);
if(arg.equals("Open network applet from server"))
msg += "Open network applet from server";
else if(arg.equals("Node File"))
msg += "Node File";
else if(arg.equals("Link File"))
msg += "Link File";
else if(arg.equals("Incident File"))
msg += "Incident File";
else if(arg.equals("TFRU File"))
msg += "TFRU File";
else if(arg.equals("Node File"))
msg += "Node File";
else if(arg.equals("Results"))
msg += "Results";
else if(arg.equals("Analysis"))
msg += "Analysis";
else if(arg.equals("help"))
msg += "help";
else if(arg.equals("Word File"))
msg += "Word File";
else if(arg.equals("Pdf File"))
msg += "Pdf File";
else if(arg.equals("HTML File"))
msg += "HTML File";
ColorMenu.msgs = msg;
//System.out.println(ColorMenu.msgs);
colorMenu.repaint(); //line 139
}
public void itemStateChanged(ItemEvent ie) {
colorMenu.repaint();
}
}
and on executing it i get the following exception :
Exception occurred during event dispatching:
java.lang.NullPointerException
at MyMenuHandler.actionPerformed(ColorMenu.java:139)
at java.awt.MenuItem.processActionEvent(Unknown Source)
at java.awt.MenuItem.processEvent(Unknown Source)
at java.awt.MenuComponent.dispatchEventImpl(Unknown Source)
at java.awt.MenuComponent.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
i camt understand why...
..please help..what i think is the class MyMenuHandler is not able to execute the command colorMenu.repaint(),but i dunno why because in the very next line it is executing the same command without any problem as u can see in the method itemStateChanged(ItemEvent ie)..
please hlp guys..i would really appreciate it..
regards
karan
