Mona M. Everett, Ph.D.

everett@txdirect.net

Writing to the Java Console
Before you try out these techniques, open the Java console. You can find it under the OPTIONS menu in Netscape. When you have it open, click on the clear button to remove its default message. One thing to note is that the console is NOT a \"stay on top \" window. It will immediately disappear behind any other window on which you click.

ConsoleTest
This code is straight from Netscape's example. Below are a button and a text field. Type whatever you want into the text field and click the button labeled "Write". Find the console, which is likely now under Netscape, and you will see that your message has been printed to the console.

The console contents are persistent; if you close and open the console, your text will still be there. Unfortunately, the console does not act as an input device; you cannot read it. The "Write" button contains an onclick routine,

• onclick="consoletest(this.form.mytext.value)",

which calls this function:

• function consoletest(astr)
  {
  • var System = java.lang.System
    System.err.println(astr)
  }

For our next example, let's do something a little more sophisticated and, in the process, we will use the new split method of the string object. The split method has the following syntax:

• var anArray = mystring.split(separator)

Note that the method constructs the new array for you. You can find the length with

• var l = anArray.length

We will also compare the ease of debugging with alert boxes, which up to now have been your only choice, and console debugging.
In a Netscape 2.0 page, we calculate a mean and standard deviation of some values. Each has to be entered into an input box, which means that the number of values one can input is limited by the number of input boxes. In this case, we will simply provide a text area and a place to provide the separator which you will use. The example uses a comma as a separator but you can experiment with different ones. The input controls are followed by four buttons:

See Array

Shows you the array it made from the string

Debug with Alert Boxes

Debugs the printarray function with alert boxes

Debug with Console

Debugs the printarray function with console output

Calculate

Calculates the statistics and prints them to the console

21.6,22.8,19.3,14.4,20.2,21.1,23.0Separator Character: Debug On:

This section uses a simple applet developed by Morphic Molecules. It just presents a single line of text in a pleasant setting. It does not scroll, blink, bounce or fade. While these special effects might seem nifty, they are really annoying on a fast computer where text scrolls, blinks, bounces, or fades so fast that the use cannot read it. Unlike most applets, its parameters are addressable and, therefore, accessible to Javascript.
In order to use the applet, download the class file and place it in the same directory as your html file (or set the code base parameter to where you are going to put it). You can also download the source, which could have a number of enhancements made to it. Get both the class and the source along with a short HTML file in a zip file if you wish. If you use Symantec's Cafe to build Java applets, download a zip file with the complete project files.
This applet has ten variables which have public get and set methods. Set methods take a single string parameter and get methods return a single string parameter.
Variables passed via applet parameters and get/set methods are error checked. Variable set by direct access by Javascript are NOT checked at all. Be careful! Further, some variable types cannot be directly passed, such as colors, where a string representation of a color must be laboriously converted into a color object. Consequently, the variables are private but accessible with get and set methods.
The following table describes these variables, their uses and the methods available to get and set them.

Public variables of the MessageBox class

Property	Type	Permissible Values	Notes
vmargin applet.setVMargin(string) string = applet.getVMargin()	integer	any integer	Values should be small; Will be used for both top and bottom margins. Defaults to 10
hmargin applet.setHMargin(string) string = applet.getHMargin()	integer	any integer	Values should be small; Will be used for both top and bottom margins. Defaults to 10
borderwidth applet.setBorderWidth(string) string = applet.getBorderWidth()	integer	any integer	Values should be small. Will be used to determine width of border around the applet. Defaults to 1. Set to 0 to specify no border.
theFontName applet.setFontName(string) string = applet.getFontName()	string	Can only be Courier, Helvetica, and Roman	Font that message is printed in. Defaults to Courier.
theFontStyle applet.setFontStyle(string) string = applet.getFontStyle()	string	Can only be plain, bold, italic, and bolditalic	Style that message is printed in. Defaults to bold.
theFontSize applet.setFontSize(string) string = applet.getFontSize()	integer	any legitimate font size	Defaults to 14
theMsg applet.setMsg(string) string = applet.getMsg()	string	Message you want presented	Applet will clip your message if it does not fit.
justification applet.setJustification(string) string = applet.getJustification()	string	Allowed values are left, right, and center	Justification of Message Allowed values ; Defaults to center
theFontColor applet.setFontColor(string) string = applet.getFontColor()	string	Allowed values are red, green,blue,pink, orange, magenta,cyan,white, yellow, gray, and black	Message will be drawn in this color. Defaults to blue.
theBGColor applet.setBGColor(string) string = applet.getBGColor()	string	Allowed values are red, green,blue,pink, orange, magenta,cyan,white, yellow, gray, and black	Background rectangel, determined by vmargin and hmargin, will be drawn in this color. Defaults to yellow
theBorderColor applet.setBorderColor(string) string = applet.getBorderColor()	string	Allowed values are red, green,blue,pink, orange, magenta,cyan,white, yellow, gray, lightgray, darkgray,and black	Border will be drawn in this color. Defaults to blue
theInset applet.setInset(string) string = applet.getInset()	string	Allowed values are none, raised, and lowered. Empty string also causes none.	Defaults to none.

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Font size

If you set the font size by typing in the edit box, it will not happen until you click on something else which can receive focus.

Margins

Margins, especially the vertical margin, do not set correctly.

Clipping

The applet does not clip the message. If you make the font too big, it will overrun the intended area

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