16.3 Type-Wrapper Classes
Each primitive type (listed in Appendix D) 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. This is important because the data structures that we reuse or develop in Chapters 16–21 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 ...
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