According to what Wikipedia says to my question "What is a wrapper class in Java":
A primitive wrapper class in the Java programming language is one of
eight classes provided in the java.lang package to provide object
methods for the eight primitive types. All of the primitive wrapper
classes in Java are immutable. J2SE 5.0 introduced autoboxing of
primitive types into their wrapper object, and automatic unboxing of
the wrapper objects into their primitive value—the implicit conversion
between the wrapper objects and primitive values.
Wrapper classes are used to represent primitive values when an Object
is required. The wrapper classes are used extensively with Collection
classes in the java.util package and with the classes in the
java.lang.reflect reflection package.
