Windows

On Windows, Firefox can be used with Sun's Java Runtime Environment (JRE) 1.4 and above. It is possible to install the latest version from within Firefox, using XPInstall technology: http://www.java.com/en/download/

Linux

Firefox is compiled with gcc 3.2.3, so a compatible version of the Java plugin must be used. On Linux, Firefox requires JRE 1.4.2 or later (http://java.sun.com/j2se/1.4.2/download.html).

If you are using an older Linux distribution, you may need to install the gcc3 support libraries, as the gcc 3.2 version of the Java plugin requires libgcc_s.so.1 to operate. You may be able to find packages using Google.

If you are using an old or unofficial build of Firefox, you can check which compiler was used by entering about:buildconfig in the location bar and pressing enter. You will see a line such as gcc version 3.3 20030226 (prerelease) (SuSE Linux), which will show the compiler that was used. If gcc2.9x was used, you need to use the ns610 plugin, not the ns610-gcc32 plugin.

Mac OS X

Java software can be downloaded directly from Apple (http://www.apple.com/java/).
