Lesson: Numbers and Strings
        
This section begins with a discussion of the 
Number 
class (in the 
java.lang package) and its subclasses. In particular, this section talks about the
situations where you would use instantiations of these classes rather than the
primitive data types. Additionally, this section talks about other classes you might need to work 
with numbers, such as formatting or using mathematical functions to complement the 
operators built into the language. 
Strings, which are widely used in Java programming, are a sequence of characters. 
In the Java programming language, strings are objects. This section describes using the 
String 
class to create and manipulate strings. It also compares the 
String and 
StringBuilder classes.