The Hello World Applet

Editorial Note: I have removed some of the links on this page because the tutorial has been updated; the old links don't work, and the applet code has been changed since this blog entry was made.

So the "next" lesson in the trail is Getting Started with Applets. I hate hello world, but after the last lesson I'm quite pleased to see it. At least it provides a scrap of code to play with. If I can embed this applet into my web page, it will improve my understanding, and if it works, it will make me feel better. So to facilitate the process, I check out the source code for the page.

The first thing I notice is that the code calling the applet on this page is completely different to the example on the previous page. The example given was:

 <applet code=AppletWorld.class

width="200" height="200">

</applet>

But the code used to call the Hello World applet is:

<applet code="HelloWorld.class"

codebase="examples/"   

archive="helloWorld.jar"   

width="150" height="30">

</applet>

That looks more like a jnlp file than the example Linkgiven, and it certainly makes it harder to copy and paste. The first question is why, if we need a jar file to run this applet, was it not mentioned on the all informative index page. And if there isn't room to tell the whole story on that page, why tell any part of it at all.

To test this, I'll compile Hello World from the source code given here, and try running it with the code given on the index page. I'll insert:

    <applet code="HelloWorld.class"

width="150" height="50">

</applet>

To my amazement, it works, not only on my server but also on my ISP hosted page.

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