All values with this class can be used as logic values. Some of the more "empty" ones, like new int[0], 0, "" and null represent logical falsity, while most other values (like new int[]{0}, 1 or "Hello, world") represent logical truth.
Now, logical expressions like a and b are evaluated like this:
First, check if a is true. If it is not, then simply return it. If it is, then simply return b (which will represent the truth value of the expression.) The corresponding logic for a or b is: If a is true, then return it. If it isn't, then return b.
This mechanism makes "and" and "or" behave like the boolean operators they are supposed to implement, but they also let you write short and sweet little conditional expressions. For instance, the statement
if(!a.equals("")){
System.out.println(a);
}else{
System.out.println(b);
}
Could instead be written
System.out.println($(a).or(b));
(this description is extracted from the article "Instant Python"- http://hetland.org/writing/instant-python.html with some modifications that reflects the Java syntax and types)