Programming and Problem Solving with Java

2.1 The Elements of Java Programs | 59

They store “Introduction to “as the value for constantWORD1. The string “Programming and
Problem Solving “is stored in the variable word3, and we store “with Java”in the constant WORD5.

Assignment and Expressions

Up to this point, we’ve looked at ways of declaring fields in a class. As part of the declara-
tion, we can give an initial value to a field. Now we turn our attention to ways of acting, or
performing operations, on values in fields.

Capitalization of Identifiers

Programmers often use capitalization to provide a quick, visual clue as to what an identifier

represents. Different programmers adopt different conventions for using uppercase letters and

lowercase letters. Some use only lowercase letters, separating the English words in an identifier

with the underscore character:

pay_rate emp_num pay_file

The convention used by many Java programmers and the one we use in this book is the follow-

ing:

• Variables and methods begin with a lowercase letter and capitalize each successive English
  word.
  lengthInYards middleInitial hours


• Class names begin with an uppercase letter but are capitalized the same as variable names
  thereafter.
  PayRollFrame Sample MyDataType String
  Capitalizing the first letter allows a person reading the code to tell at a glance that an identi-
  fier represents a class name rather than a variable or method. Java’s reserved words use all
  lowercase letters, so the type charis lowercase.Stringis a class, so it begins with a capital let-
  ter.


• Identifiers representing named constants are all uppercase with underscores used to separate
  the English words.
  BOOK_TITLE OVERTIME MAX_LENGTH
  These conventions are simply that—conventions. Java does not require this particular style
  of capitalizing identifiers. You may wish to write your identifiers in a different fashion. But
  whatever method you use, it is essential that you maintain a consistent style throughout your
  code. A person reading your code will be confused or misled if you use a random style of capi-
  talization.