2.3 Java的識別名稱(Identifier)

授課教師：陳慶瀚

WWW : http://www.miat.ee.isu.edu.tw/java

E-mail : pierre@isu.edu.tw  　

Identifiers are the names of variables, methods, classes, packages and interfaces. Unlike literals they are not the things themselves, just ways of referring to them. In the HelloWorld program, HelloWorld, String, args, main and System.out.println are identifiers.

Identifiers must be composed of letters, numbers, the underscore _ and the dollar sign $. Identifiers may only begin with a letter, the underscore or a dollar sign.

Each variable has a name by which it is identified in the program. It's a good idea to give your variables mnemonic names that are closely related to the values they hold. Variable names can include any alphabetic character or digit and the underscore _. The main restriction on the names you can give your variables is that they cannot contain any white space. You cannot begin a variable name with a number. It is important to note that as in C but not as in Fortran or Basic, all variable names are case-sensitive. MyVariable is not the same as myVariable. There is no limit to the length of a Java variable name. The following are legal variable names:

• MyVariable
• myvariable
• MYVARIABLE
• x
• i
• _myvariable
• $myvariable
• _9pins
• andros
• ανδρος
• OReilly

The following are not legal variable names.

• My Variable // Contains a space
• 9pins // Begins with a digit
• a+c // The plus sign is not an alphanumeric character
• testing1-2-3 // The hyphen is not an alphanumeric character
• O'Reilly // Apostrophe is not an alphanumeric character
• OReilly_&_Associates // ampersand is not an alphanumeric character

物件導向程式設計

義守大學電機系 陳慶瀚

2001.10.02