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Java Language Fundamentals 707

BD4

try

Declaration modifiers abstract

final

private

protected

public

static

Used with classes and methods class

extends

implements

import

instanceof

interface

native

package

throws

transient

volatile

Reserved for future use const

goto

Java Identifiers ....................................................................................................

Anidentifieris a name that you supply for a variable, class, or other program element.

Java is very flexible when it comes to identifiers. They can be any length and can contain

letters, the underscore character, the dollar sign character, and the digits 0 through 9

(although the first character of an identifier cannot be a digit). By letters, Java does not

mean only the 26 characters of the English alphabet, but all the thousands of characters

from various languages that are represented in the Unicode character set. To be specific,

all Unicode characters above hex value 00C0can be used in a Java identifier. Here are

some examples:

interestRate

$_9

ø9ú

As with any language, you cannot use keywords as identifiers. Also, it is wise program-

ming practice to use identifiers that describe the item they refer to. In the list above, the

first identifier adheres to this rule. The other two, although perfectly legal, break the rule

and should be avoided.

TABLEB4.1 continued

Category Keywords

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