Nearly every infected PC I have looked at in the past few years contained a java virus / trojan. Laptops, desktops. New, old all had the same common vulnerability: Java.
Some of the users of those PCs did not auto update. Some did and still wonder why they were infected.
Some didn't even know what Java was ...
So here's the solution: Uninstall Java.
What is the point of it?
There is only one site I (used) to visit in which I needed Java to run properly. That site is antiquated and past its best. A bit like Java.
When I installed Open Office there was a nag screen, which asked if I wanted Java. Uh no. And OO still works fine.
When I used Jedit it wanted Java. Uh no. I quickly located an alternative editor.
Java is installed by default on most box PCs. Uninstall it and your average Joe user will rarely get infected. They won't miss Java. They don't even know what it is.