COMP 310

Java Tips and Traps

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This is a collection of suggestions and warnings about common Java problems.

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Application Blocked by Security Settings

Symptoms:  

 

Possible Cause:

The Java security settings in your system are not allowing the desired application or applet to run because it is untrusted.  

 

Try this:

Add the application or the applet's URL to the "Exception Site List" in the Java Control Panel

  1. Find the Java Control Panel in your system:
  2. Under the "Security" tab, click on the "Edit Site List" button
  3. Add the URL of the application

 

Enable the Java console

When one is having problems launching or running Java applets or Java Web Start ("JWS") applications, it is highly recommended that the Java console be enabled so one can see error messages when applets or JWS applications start up and run.   This can help you debug problems by showing you the Java error messages that are generated.  Select these options under the "Advanced" tab of the Java Control Panel:

 

References:

 

Applet Won't Run in Browser

Symptoms:

 

Possible Cause:

The latest version of Chrome and the Microsoft Edge browser do not support the running of Java applets.   (Technically, they no longer support the "NPAPI" ("Netscape Plug-in API") plugin format that Java uses due to security and other concerns.)

The security settings in the browser do not allow the applet to run.

Try this:

 

References:


© 2017 by Stephen Wong