Modern Java IDEs like Symantec's Visual Cafe and Inprise's JBuilder offer advanced applet debugging facilities. However, if you develop your applets using only the freely distributed JDK, it might be very hard to see which particular things go wrong when they do. Additionally, you may encounter situations where your applet behaves fine under Netscape Navigator and strangely under Internet Explorer (or vice versa). Different Java Virtual Machines may have different levels of tolerance for a bug. Sometimes, the bug lies in the actual virtual machine implementation.
The lack of information provided by the browser about applets can be frustrating. However, there is a way to display a debugging console, which will provide developers with additional information. For example, an uncaught exception will generate an exception trace, telling you which method and which exception were involved with the exception. Latest versions of both Netscape Navigator and Internet Explorer have debugging consoles for Java.
To launch the Java Console in Netscape Communicator:
Load any page with an applet, and then select the following menu option.
Communicator -> Tools -> Java Console
To view the Java Console in Netscape Communicator, first, you must ensure that the Java console is enabled. Make sure that the following checkbox is checked:
Tools -> Options -> Advanced -> Java Console Enabled
Next, load any page with an applet, and then select the following menu option:
View -> Java Console
Both of these consoles provide useful debugging information, which can assist you in tracking down potential problems.