A close look at the NetBeans output

My intention at this point was to visit the lesson on running jar package software, but NetBeans, after building the app, suggested running it with the following command:

java -jar ActiveMathJA002.jar

I think I'll try that first, as I have a command window open and all the files are in the right place.

Well the command worked OK, and my app opened, but it didn't work properly. Months have passed since I drafted the code, but it seemed as if an early version was running. Why would it work one way when run from within NetBeans and another when run as a stand-alone?

I commented earlier that I was surprised to see draft versions included in the NetBeans built jar file. I think I'll take the drafts out. While I'm at it I'll check the dates of the main class files.

The date on the class files extracted from the jar file is Aug 31 2008. That seems wrong, because I ran the build command yesterday. Checking out the build folder, there are two class files with slightly more recent dates (September 2 2008). I'll use them and rerun the command to build the jar file with the specified entry point and see what happens.

Now it's looking for 

AMJFormA002$2.class
which I assumed was an early draft. So I'll add that back to the folder I'm using for my manual build. Now the app runs pretty much as it does from NetBeans. There is some stuff being written to standard output which I thought I'd commented out, but besides that the basic execution path seems to be the same.

A number of questions arise from all of this:

  • Why don't the built file dates match the last time I ran the build command?
  • Why is has the jar file an earlier date than the class files?
  • Why are three class files needed for the main class?
  • Why was the entry point not included in the manifest?

It turns out that the answer to all of but one of these questions was that for some reason I was running NetBeans from a backup drive, and therefore running the tests on the wrong files. When I looked closely at the correct jar file, everything was as it should be. The main class still seemed to made up of three files, but apart from that everything was fine.

Comments

Post a Comment

Popular posts from this blog

A few notes on JavaScript

I am one the 99% of the world who has long nursed the misconception that JavaScript has something to do with Java. And why not? The name sort of implies it. It was only after I searched without success on the Java Tutorial site for some mention of JavaScript that I stumbled across the knowledge that JavaScript was in fact developed by Netscape, under the name LiveScript. Armed with that knowledge, it is not surprising to find the best reference information on Mozilla site. According to Wikipedia , the nonsensical name choice had something to do with Netscape wanting to cash in on the popularity and cachet of Java, and Sun wanting support for Java technology in the then popular Netscape browser. For a while only the Netscape family of browsers supported JavaScript. Microsoft later produced what it calls JScript to run in its browser. JScript is similar but not identical to Javascript. According to Foldoc JavaScript runs a hundred times slower than C , and ten
Read more

Forum Comments on Java Applets

It is so long since I last posted on the once was Sun/Java now is Oracle developer forum my account seems to have been ditched. While I wait to have it resurrected I've done a little searching in the Java Database Connectivity (JDBC) forum using the search term "Applet". My first search, using the default 3 month period, yielded nothing. No one had posted anything about or even mentioned Applets in the last three months. So either they are very easy to use and work very well, so hardly anyone has any problems with them, or maybe ... not very many people use them at all. My stomach was beginning to churn a bit, when I extended the search period to the current year - and with good reason. Somebody, a little bit like me I think, had written a game in an applet, and wanted to record top scores in a database. He described his connection problem in this thread , and the first reply began: Doing JDBC calls from an Applet is such a bad idea that I am glad y
Read more

Creating a Custom Swing Component

Image
I always return to my blog when I'm stuck, and I'm stuck right now. I want to create a custom Swing component. Specifically, I want something like a JProgressBar , with the following changes: In place of a flat Foreground color, I want a rainbow spectrum, showing only the red range for low Values, and the whole spectrum for values close to the Maximum value; Instead of a rectangular box, I want the progress "bar" to take the shape of a normal, or Gaussian, distribution curve; I want progress to be displayed by the area under the curve, rather than by a simple linear scale along the x axis. It's not that there isn't stuff out there. I have five tabs open in my browser, specifically addressing the creation of custom components in Swing, as well as the source code for the JProgressBar . It is that, like everything to do with Java, it is bloody difficult to read. I shall begin from the horse's mouth as it were, with an article on the Java
Read more