Android How to Program, 3/e

J.3 Type-Wrapper Classes for Primitive Types

Each primitive type (listed in Appendix L) has a corresponding type-wrapper class in package java.lang. These classes are called Boolean, Byte, Character, Double, Float, Integer, Long and Short. These enable you to manipulate primitive-type values as objects. Java’s reusable data structures manipulate and share objects—they cannot manipulate variables of primitive types. However, they can manipulate objects of the type-wrapper classes, because every class ultimately derives from Object.

Each of the numeric type-wrapper classes—Byte, Short, Integer, Long, Float and Double—extends class Number. Also, the type-wrapper classes are final classes, so you cannot extend them.

Primitive types do not have methods, ...