Java is a bit of software one does appently not really need, although most of us have on our PCs. Some experts say it is security risk; others say it is not too bad. But more annoyingly, it keeps on asking you to update it, and by default, when you do this it will install a bit of scumware called Ask, which highjacks your search engine and takes quite a bit of work to remove from a computer.
If you are careful, it is possible to do the Java thing without the Ask scumware, but it is tedious. So having spent half an hour of my life removing Ask, I also uninstlled Java.
So far, the world has not collapsed.