A computer virus is a program written by someone who to maliciously damage the FILES you have stored on your disks or your computer's disk itself. To encounter a virus from across the Internet, you MUST download and run a program. Unfortunately, with Java applets, a remote sever downloads the applet to a browser on your system which, in turn, runs the applet. At first glance these downloaded Java applets are an ideal way for MALICIOUS programmers to create viruses. Luckily, the Java developers designed Java with networking in mind. Therefore, Java has several built-in security defenses which reduce a programmer's ability to use Java to create a virus.
First, Java applets cannot read or write local files that reside on your disk. In this way, the applet cannot store the virus on your disk or attach the virus to a file. That the applet simply cannot perform disk INPUT and output. Second, Java applets are "blind" to your computer's memory layout. Specifically, Java applets do not have pointers to memory, and programmers cannot use this traditional back door to your computer. Third, Java cannot use memory outside its own memory space. By building these precautions into programming language itself, the Java developers have GREATLY impaired Java's use in creating and transmitting computer viruses.

A computer virus is a program written by someone who to maliciously damage the files you have stored on your disks or your computer's disk itself. To encounter a virus from across the Internet, you must download and run a program. Unfortunately, with Java applets, a remote sever downloads the applet to a browser on your system which, in turn, runs the applet. At first glance these downloaded Java applets are an ideal way for malicious programmers to create viruses. Luckily, the Java developers designed Java with networking in mind. Therefore, Java has several built-in security defenses which reduce a programmer's ability to use Java to create a virus.
First, Java applets cannot read or write local files that reside on your disk. In this way, the applet cannot store the virus on your disk or attach the virus to a file. That the applet simply cannot perform disk input and output. Second, Java applets are "blind" to your computer's memory layout. Specifically, Java applets do not have pointers to memory, and programmers cannot use this traditional back door to your computer. Third, Java cannot use memory outside its own memory space. By building these precautions into programming language itself, the Java developers have greatly impaired Java's use in creating and transmitting computer viruses.