Java Identifier Definition and Examples

Java Identifier Definition and Examples A Java identifier is a name given to a package, class, interface, method, or variable. It allows a programmer to refer to the item from other places in the program. To make the most out of the identifiers you choose, make them meaningful and follow the standard Java naming conventions. Examples of Java Identifiers If you have variables that hold the name, height, and weight of a person, then choose identifiers that make their purpose obvious: String name Homer Jay Simpson; int weight 300; double height 6; System.out.printf(My name is %s, my height is %.0f foot and my weight is %d pounds. Doh!%n, name, height, weight); This to Remember About Java Identifiers Since there are some strict syntax, or grammatical rules when it comes to Java identifiers (dont worry, they arent hard to understand), make sure youre aware of these dos and dont: Reserved words  like class, continue, void, else, and if cannot be used.Java letters is the term given to the acceptable letters that can be used for an identifier. This includes not only regular alphabet letters but also symbols, which just includes, without exception, the underscore (_) and dollar sign ($).Java digits include the numbers 0-9.An identifier can begin with a letter, dollar sign, or underscore, but not a digit. However, its important to realize that digits  can  be used so long as they exist after the first character, like e8xmpleJava letters and digits can be anything from the Unicode character set, which means characters in Chinese, Japanese, and other languages can be used.Spaces are not acceptable, so an underscore can be used instead.The length does not matter, so you can have a really long identifier if you choose.A compile-time error will occur if the identifier uses the same spelling as a keyword, the null literal, or boolean literal.Since the list of SQL keywords may, at some point in the future, include other SQL words (and identifiers cant be spelled the same as a keyword), its usually not recommended that you use an SQL keyword as an identifier. Its recommended to use identifiers that are related to their values so theyre easier to remember.Variables are case-sensitive, which means myvalue does not mean the same as MyValue Note:  If youre in a hurry, just take away the fact that an identifier is one or more characters that come from the pool of numbers, letters, the underscore, and the dollar sign, and that the first character must never be a number. Following the rules above, these identifiers would be considered legal: _variablename_3variable$testvariableVariableTestvariabletestthis_is_a_variable_name_that_is_long_but_still_valid_because_of_the_underscoresmax_value Here are some examples of identifiers that are not valid because they disobey the rules mentioned above: 8example(this starts off with a digit)exaple (the plus sign isnt allowed)variable test (spaces are not valid)this_long_variable_name_is_not_valid_because_of_this-hyphen(while the underscores are acceptable like in the example from above, even the one hyphen in this identifier renders it invalid)