Java is a programming language promoted by Sun Microsystems.
When it comes to deploying programs on the Internet, Java has
numerous advantages over traditional languages such as Visual Basic,
C, and C++. Two significant advantages of Java are:
Java programs are much smaller (meaning they
download quickly).
Java can run on almost all computers and
operating systems (e.g., Linux, Mac, Solaris, Windows, etc.).
This page will help you troubleshoot problems
running Java applets in your browser. This page was written
primarily to help people run the Health and Fitness Calculator, but the tests
are appropriate for all Java applets.
Test Applets
A gray, rectangular Java applet should be
displayed below this paragraph (it may take a minute or two for the
applet to appear). This applet tests your browser's ability to run a
Java version 1.0 applet. If the gray rectangle is not displayed, if
the rectangle is displayed but it does not contain several lines of
text, or if the words "Your browser is unable to run
TestJava10.class" are displayed, your browser or Internet
provider does not support Java applets. Scroll down this page for
additional information.
A gray, rectangular Java applet should also
be displayed below this paragraph (it
may take a minute or two for the applet to appear). This applet
tests your browser's ability to run a Java version 1.1 applet from a
jar file. If the gray rectangle is not displayed, if the rectangle
is displayed but it does not contain several lines of text, or if
the words "Your browser is unable to run TestJava11.jar"
are displayed, your browser or Internet provider does not support
Java 1.1 applets. Scroll down this page for additional information.
Interpreting the
Test Results
If both of the
above applets displayed correctly:
Your browser is correctly configured to run
Java applets.
If only the
first of the above applets displayed correctly:
Your browser supports Java version 1.0, but
not version 1.1 applets.
If neither of
the above applets displayed correctly, either:
Your browser does not support Java.
Your Internet provider's firewall (or proxy)
is blocking Java applets.
Your browser is configured to block Java
applets (unlikely).
General Problem Solving
If you suspect your browser does not support
Java (or if it only supports Java version 1.0), follow these links
to download the most recent version of either the Microsoft Internet Explorer or the Netscape Navigator (contained within the Netscape Communicator).
If you are using Internet Explorer and see the following message in your
comment line above the address field, "To help protect your security,
Internet Explorer has restricted this file from showing active content that
could access your computer. Click here for options", click the comment line
and choose the "Allow blocked content" option.
If you suspect your Internet provider is
blocking Java applets with a firewall or proxy (this is very common
if you access the Internet from your office network, and not very
common with commercial ISPs), ask your system administrator if this
is the case and if so, ask if they'll change it. System
administrators often block Java applets as a security precaution as
they don't understand that Java applets are extremely safe and cannot modify anything on your computer.
If you suspect your browser is configured to
block Java applets, some browsers do have a "disable Java"
option. You can access this setting in version 5.x of the
Microsoft Internet Explorer by choosing “Tools | Internet
Options | Security | Internet | Custom Level | Java” (in
version 4.x, choose “View | Internet Options | Security |
Custom | Settings | Java”), This should not be set to
"Disable Java" (we suggest the default setting of
"High Security").
The Java
Console
You can often learn why you are unable to run
Java applets by displaying the Java
Console from within your browser and then attempting to run a
Java applet. The Java Console may display messages informing you
that the Java applet was not found, that it caused an error (an
'Exception'), that it was blocked by a firewall, etc. You can copy
and email the contents of the Java Console to the developer of the
Java applet for assistance.
Displaying the Java
Console from the Microsoft Internet Explorer
Choose View on
the main menu and then choose Java
Console.
If
there is not a Java Console choice in
the View menu:
In version 5.x, choose Tools on the main menu and then choose Internet Options. In version 4.x, choose View on the main menu and then choose Internet Options.
Click on the Advanced tab in the Internet Options dialog.
Use the scrollbar to scroll down the list to
the Java VM section.
Make sure the Java
console enabled checkbox contains a check.
Exit and restart the Internet Explorer.
Choose View on
the main menu, and then choose Java
Console.
Displaying the Java
Console from the Netscape Navigator
Choose Communicator on the main menu.
Choose Tools
and then Java Console from the Tools submenu.
Copying the Contents
of the Java Console
Click and drag your mouse within the Java
Console to select all of the text.
Press the Ctrl
key, and while still pressing Ctrl,
press the C key. (This copies the
selected text to the clipboard.)
Release both keys.
Pasting the Contents
of the Java Console
Click in the desired document (e.g., in an
email).
Choose Edit
from the main menu.
Choose Paste.
Specific Java Console Messages
The following are a few of the numerious
error messages that can appear in the Java Console.
If a message similar to "java.lang.NoSuchMethodError:
java.awt.TextArea" is displayed, you probably need to
upgrade your browser.
If a message similar to "Cannot find class
java/awt/event/ActionListener" is displayed, you probably
need to upgrade your browser.
If a message containing the term "FileNotFoundException" is displayed,
it probably means either (1) you need to upgrade your browser (i.e.,
the browser doesn't support jar files, so it can't find the init()
class) or (2) something is missing on the server (i.e., the
developer of the applet forgot to put an important file on the
server).
