Your web browser might need to be configured in a certain way to enable Java functionality, either by creating a symlink in your browser's plugin directory to the Java plugin file, or otherwise specifying in the browser's configuration to enable Java support.
Remember to restart your browser after the installation of Java and creation of the symlink so that the plugin will be recognized
Browser plugin or configuration
The following browsers get Java support by creating a symlink to the Java plugin library in the browser's plugin directory
The following browsers get Java support by enabling an option in the browser's configuration
Exactly what the symlink needs to point to depends on what version of gcc your browser was compiled with, and what browser you have. And the path depends on what JRE/SDK you installed.
Mozilla Firefox 1.0 (gcc 3.3.x) Java Browser Plugins Installation in debian
Create a symlink in Firefox's plugin directory that points to the Java plugin library file (example with JRE 1.5.0).
Mozilla 1.0 (gcc 2.9x)Java Browser Plugins Installation in debian
Mozilla 1.0 from the old stable Debian 3.0 'woody' is compiled with gcc 2.9x and thus it needs to use the pre-gcc3.2 plugin. The installation procedure has created a symlink (called libjavaplugin.so in the Mozilla's plugin directory) to the plugin, but it is for the post-gcc3.2 plugin, so you can remove that symlink while you are at it (example with JRE 1.5.0):
Opera 8.5Java Browser Plugins Installation in debian
Opera doesn't need any symlink created, instead the path to the Java installation is set through the configuration menus in the browser.
Tools → Preferences... → Advanced → Content; check the checkbox that says Enable Java; → Java options.... In the field named Java path type the path to the lib/i386 directory of the JRE, e.g. in the case of JRE 1.5.0
/usr/lib/j2re1.5-sun/lib/i386/or e.g. in the case of JDK 1.5.0
Then click on the Validate Java path button in the dialogue, you should get a message dialogue that says The Java path seems to specify a valid directory. Select OK in all the dialogue windows, and restart the browser
Konqueror 3.4Java Browser Plugins Installation in debian
As in the case with Opera above, one does not need to create any symlinks to the plugin with Konqueror, the configuration is done from within the browser:
Select OK in and restart the browser
Galeon and EpiphanyJava Browser Plugins Installation in debian
Galeon and Epiphany are based on Mozilla, and they use the plugin directory of Mozilla, so if Java doesn't work right away in them, just follow the instructions for Mozilla above.