Implementing Comparator Interface?

overriding of the compare method.

Here's an example I found:

public class Someone {
String name;
int age;
ArrayList <Someone> listarr = new ArrayList <Someone>();
public Someone(String name1, int age1) {
name = name1;
age = age1;

[code]...

1. In the compare method, what happens when it returns one of the 0, -1, or 1? How does returning such values contribute to the sorting process? How does it take in information (like I know it does through the parameters, but how exactly)?

2. Why do we use the class name for the generics?