Chapter 8. Primitives as Types

 

I'm gonna wrap myself in paper, I'm gonna dab myself with glue, Stick some stamps on top of my head! I'm gonna mail myself to you.

 
 --Woody Guthrie, Mail Myself to You

The separation of primitive types (byte, float, and so on) and reference types (classes and interfaces) is a trade-off between efficiency and familiarity versus expressiveness and consistency. An object may incur too much overhead where a plain int will do, while an int may be fast and convenient until you need to store it into a hashtable. To smooth this separation, the Java programming language provides a wrapper class corresponding to each of the primitive types. Instances of a given wrapper class contain a value of the corresponding primitive type. ...

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