Getting system root directory in Java

If you are working with file-system in Java,you should understand that your program can run in other types of OS:(Windows,Unix,Linux).
These OS has own file-system structure. For example you need to read or write file in Windows,which located at disk C:\,you should write:

File root = new File("C:\\");File dir = new File(root,"someDir");File child = new File(dir,"someFile");

It’s normal,because you know that your file located at disk C:\. Remember –avoid this practice. What if your program will run in Linux? You should modify your code:

File root = new File("/");File dir = new File(root,"someDir");File child = new File(dir,"someFile");

It’s not good. Java has great way for getting root directory:

File[] roots = File.listRoots();File dir = new File(roots[0],"someDir");File child = new File(dir,"someFile");

I ran this snippet of code in my Windows machine and I got all my local disks. roots[0] is my local disk C:\.