I had recently reinstalled my system and was trying to run a simple class that consisted
of a “Hello World” program in Java. I received the following:

Compile:

$> javac LottoMain.java

Run:

$> java LottoMain

Exception in thread “main” java.lang.NoClassDefFoundError: LottoMain
Caused by: java.lang.ClassNotFoundException: LottoMain
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:319)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:264)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:332)
Could not find the main class: LottoMain. Program will exit.

The compile line completed without errrors and the LottoMain.class file was there, but
what I didn’t know was that I no longer had the current directory “.” in my CLASSPATH variable.

After adding “.” to my CLASSPATH variable the run command gave me what I was expecting.

Run:

$> java LottoMain

Hello Eric!

Updating the CLASSPATH variable in Bash:
in my home directory/.bashrc file

export CLASSPATH=$CLASSPATH:.

Tags: Java, Programming

Starting on my road to creating a Java based GUI I stumbled upon the following link within the “Creating a GUI with JFC/Swing” Train in the Java Tutorials from Oracle.

Using Swing Components: Examples

It has code examples and can really get you started on the road to a Java GUI interface.

Tags: GUI, Java, Swing

This is the First of some basic articles about creating a GUI in Java. The following code is the basis of the following series of articles. I am using the Java Swing window toolkit.

import java.awt.*;
import java.swing.*;

class FirstWindow 
{

  public static void main(String[] args)
  {
      //Create Window object and set title bar text
      JFrame frame = new frame("First Window");

      // Set the Default operation when you close the window
      // This exits the program on closing the window
      // The default behavior is to HIDE_ON_CLOSE
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      // Now we need to Display the window
      // The null argument will place the element in the center of the screen.
      frame.setLocationRelativeTo(null);
      frame.pack();
      frame.setVisible(true);
   }
}

This is enough to display a simple window, but it will probably not have any useful size associated with it and it does not do anything.

The next step will be to add some useful widgets and eventually functionality to make the window useful.

Helpful info:
Java: Great link to Swing Examples

Tags: Java, Swing

So I was charging my Droid X and noticed that while I was connected I could not use my SD card anymore. And the camera will not take any picutures if there is no SD card present.

So I pulled down the task bar and selected “USB connection” .

Once I selected the “Charge Only” option, it was smooth sailing and my SD card was available to my phone again.

This is also the place to turn on “USB Mass storage” when you are ready to copy off those pictures.

Tags: android

So I finally moved away from the iPhone(as it turned horrible when I used the “supported” update to iOs 4 on my 3g) and have gotten myself a Droid X. This phone has been awesome(and I have only had it for 2 days).

The Google driving directions app that comes with the phone has been awesome and the unified mailbox is pretty cool. The Android market has been nice and I have perused quite a few apps so far and have been very excited as to what is out there. I was a little afraid as I had heard some less then great things but am very happy to be misinformed.

I am still on the hunt for a good messaging app that supports popup messages (like the iPhone had) and also looking for a new expense receipt tracking app.

I will be following up with some useful information about using the Android OS as I have access to two of them in the house.

I am excited to have this new toy and looking forward to the things I can do with it.

Tags: android, droid, droidx, review

A quick way to test a perl module with a new method is to use a command like the following:

$ perl -MeTechTips::IssueTracking::ClearQuest -we '$tr =  eTechtips::IssueTracking::ClearQuest->new();'

This will test the new and ensure that you have the correct syntax if you do not have an easy test environment for your code, for example as I do not have a ClearQuest instance to test with.

If you are not sure of the location of where a library is being included from in Perl you can use the following command:

perl -MXML::SAX -le 'print $INC{"XML/SAX.pm"}'

This search is for the XML::SAX library and it displays the location of the SAX.pm file.

I have some scripts that were giving me the following message:
could not find ParserDetails.ini in /usr/lib/perl5/vendor_perl/5.10/XML/SAX

The way that I worked around this message was to create the ParserDetails.ini file in the /usr/lib/perl5/vendor_perl/5.10/XML/SAX directory with the following contents.

[XML::SAX::PurePerl]
http://xml.org/sax/features/namespaces = 1

Tags: perl, scripting

If you have every wanted to set certain IP addresses in your network without depending on a nameserver, you can edit the ‘hosts’ file in your operating system.  This can be done to stop access to any inappropriate sites as well.

The hosts file in Windows is:

%systemroot%System32driversetchosts

This is typically  in:

c:windowsSystem32driversetchosts

On linux this file is:

/etc/hosts

The common layout of the file is

<IP address> hostname [hostname]

So if would look something like this:

127.0.0.1  localhost
192.168.2.222 homeserver homeserver.mydomain.net
127.0.0.1 badlocation

Remember that these lookups happen before looking to a nameserver. So this will override any name lookup. So if you happen to do this on a laptop that you regularly use outside of your home network, make sure that you do not override an address that might be needed when you are not at home.

You will need appropriate privileges to access the file. So you may have to be root or use sudo on Linux and you may have to open an editor as administrator before opening the file on Windows.

Tags: Linux, Windows

This turns off word wrap in the vi window

:set nowrap

to enable it again:

:set wrap

Tags: editors, vi