Maecl, Java is a self-contained software platform that lets applications, especially Web-based ones, run equally well on Windows, Mac OS X or Linux. It has been plagued with a number of security flaws which allow hackers to easily distribute malware. As me1004 mentions in his post, it is rarely used anymore. Between the vulnerability and the minimal use, many people have chosen to disable Java altogether. This thread
may be helpful to you and outtempster #8 in disabling Java in your operating system.
Hope that helps.