Java 6 Illuminated: An Active Learning Approach, 2nd Edition

384 CHAPTER 7 Object-Oriented Programming,Part 2: User-Defined Classes

You may wonder why the compiler calls an identifier a symbol. The Java

compiler generates a symbol table as it reads your code. Each identifier you

declare is put into the symbol table, along with the identifier’s data type

and where in the program it was defined. This symbol table allows the

compiler to track the identifiers that are in scope at any given time. Thus, if

an identifier is not in scope, the compiler will not be able to find that sym-

bol in its table for that section of code.

When the client in Example 7.2 runs, it instantiates three objects, but

there is nothing mor ...