If you do have Java installed, then it has a cache of files that are downloaded. These are usually small but can take up a lot of space. It seems that by default, Java is able to have up to 1GB of space so I reduced this to 100MB.
Note: Java is serious security risk for desktop computers and you shouldn't install it. If you do need to use Java on the Mac, make sure to keep it disabled. I do not recommend installing or enabling Java.