what is a indentifier

Ads

 
 
 

Share on Google+Share on Google+

Chris Scott
what is a indentifier
2 Answer(s)      8 years ago
Posted in : Java Beginners
Ads
View Answers

September 29, 2008 at 10:25 AM


An identifier is an unlimited-length sequence of Java letters and Java digits, the first of which must be a Java letter. An identifier cannot have the same spelling (Unicode character sequence) as a keyword, boolean literal, or the null literal.

Identifier:
IdentifierChars but not a Keyword or BooleanLiteral or NullLiteral

IdentifierChars:
JavaLetter
IdentifierChars JavaLetterOrDigit

JavaLetter:
any Unicode character that is a Java letter (see below)

JavaLetterOrDigit:
any Unicode character that is a Java letter-or-digit (see below)

Letters and digits may be drawn from the entire Unicode character set, which supports most writing scripts in use in the world today, including the large sets for Chinese, Japanese, and Korean. This allows programmers to use identifiers in their programs that are written in their native languages.
A "Java letter" is a character for which the method Character.isJavaIdentifierStart(int) returns true. A "Java letter-or-digit" is a character for which the method Character.isJavaIdentifierPart(int) returns true.

The Java letters include uppercase and lowercase ASCII Latin letters A-Z (\u0041-\u005a), and a-z (\u0061-\u007a), and, for historical reasons, the ASCII underscore (_, or \u005f) and dollar sign ($, or \u0024). The $ character should be used only in mechanically generated source code or, rarely, to access preexisting names on legacy systems.

The "Java digits" include the ASCII digits 0-9 (\u0030-\u0039).

Two identifiers are the same only if they are identical, that is, have the same Unicode character for each letter or digit.

Identifiers that have the same external appearance may yet be different. For example, the identifiers consisting of the single letters LATIN CAPITAL LETTER A (A, \u0041), LATIN SMALL LETTER A (a, \u0061), GREEK CAPITAL LETTER ALPHA (A, \u0391), CYRILLIC SMALL LETTER A (a, \u0430) and MATHEMATICAL BOLD ITALIC SMALL A (a, \ud835\udc82) are all different.

Unicode composite characters are different from the decomposed characters. For example, a LATIN CAPITAL LETTER A ACUTE (, \u00c1) could be considered to be the same as a LATIN CAPITAL LETTER A (A, \u0041) immediately followed by a NON-SPACING ACUTE (, \u0301) when sorting, but these are different in identifiers. See The Unicode Standard, Volume 1, pages 412ff for details about decomposition, and see pages 626-627 of that work for details about sorting. Examples of identifiers are:

String
i3
MAX_VALUE
isLetterOrDigit



Rajanikant


September 29, 2008 at 11:02 AM


Hi friend,

Identifiers are the names of variables, methods, classes, packages and interfaces. In the HelloWorld program, HelloWorld, String, args, main and println are identifiers.

Identifiers must comply with these rules:

* The first character of an identifier must be a letter, an underscore(_), or a dollar sign($).
* The rest of the characters in the identifier can be a letter, underscore, dollar sign, or digit. Note that spaces are NOT allowed in identifiers.
* Identifiers are case-sensitive. This means that age and Age are different identifiers.
* Identifiers cannot match any of Java's reserved words.

Examples:

These identifiers are valid:

MyClass
$amount
totalGrades;
TotalGrades;
TAX_RATE
one

These identifiers are NOT valid:

My Class // spaces are not allowed
numberOf*s // the asterisk cannot be used
final // final is a reserved word
1Way // identifiers cannot start with a digit


--------------------------------------------------------------------


Visit for more information.

http://www.roseindia.net/java/

Thanks

Amardeep.

Ads









Related Tutorials/Questions & Answers:
what is a indentifier - Java Beginners
what is a indentifier  What is an identifier and what is the definition?  An identifier is an unlimited-length sequence of Java letters and Java digits, the first of which must be a Java letter. An identifier cannot
what is bit
what is bit  what is bit
Advertisements
What is procedure
What is procedure  What is procedure in computers? What are the primary categories of procedures
what are indices?
what are indices?  what are indices
what is collections?
what is collections?  what is collections
What is this keyword?
What is this keyword?  What is this keyword
what is Savepoint ?
what is Savepoint ?  what is Savepoint
What is a "constraint"?
What is a "constraint"?  What is a "constraint
What is Index?
What is Index?  What is Index
What is SQLLoader?
What is SQLLoader?  What is SQLLoader
What is DML?
What is DML?  What is DML
What is an interface?
What is an interface?  What is an interface
What's PHP ?
What's PHP ?  What's PHP
What is VLR ?
What is VLR ?  hii, What is VLR
What is Trigger?
What is Trigger?  What is Trigger
What is ActionServlet?
What is ActionServlet?  What is ActionServlet
What is FBT
What is FBT   hello, What is FBT
What is JDBC?
What is JDBC?  What is JDBC
What is an Abstract Class and what is it's purpose?
What is an Abstract Class and what is it's purpose?   Hi, What is an Abstract Class and what is it's purpose? Thanks
What is a transaction and what are ACID properties?
What is a transaction and what are ACID properties?  What is a transaction and what are ACID properties
What is DataAccessException?
What is DataAccessException?  Hi, What is DataAccessException? thanks
What is SQLExceptionTranslator?
What is SQLExceptionTranslator?  Hi, What is SQLExceptionTranslator? Thanks
What is casting?
What is casting?   Hi, What is casting? thanks
What is IOC ?
What is IOC ?  HI, What is IOC or Dependency Injection? Thanks
What is Externalizable?
What is Externalizable?   Hi, What is Externalizable? Thanks
What is the % operator?
What is the % operator?   Hi, What is the % operator? thanks
What are Struts?
What are Struts?  What are Struts? Can anyone explain me what are the Struts framework and what are its uses? Thanks
What is WAP?
What is WAP?  What is WAP?   Hi, Check the tutorial: What is WAP? Thanks
What is CRM?
What is CRM?  Can anyone tell me What is CRM? Thanks
what is RUP?
what is RUP?  hello, what is RUP??   hii, RUP is stands for Rational Unified Process
What is a tuple?
What is a tuple?  What is a tuple?   hi, A tuple is an instance of data within a relational database. Thanks
Tutorials   
Java Spring Hibernate Struts Training ClassNotFoundException HttpRequestInterceptor java.lang.noclassdeffounderror: org/apache/http/httprequest noclassdeffounderror: org/apache/http/client/methods/httpurirequest java.lang.NoClassDefFoundError: org/apache/http/client/HttpClient How do I resolve this Java Class not found exception? httpclient java.lang.NoClassDefFoundError Apache Commons ioutils maven dependency Read/Convert an inputStream to a String What is the meaning of Java Platform? Why Java is a platform independent language? What is the benefits of learning Core Java? Which technology should I learn after Java? What is array in java with example? How to Convert ArrayList to Array? How to substring in Java? How to format number in Java? What is instance variable in Java? How to download MySQL JDBC driver? What is Calendar class in Java? Which is the best Java tutorials for beginners? How to rename a file in Java? How to delete file in Java code? How to get day from date in Java using Calendar? How to get day of week in Java? How to calculate Date Difference in Java? How to compare date in Java? How to declare array in Java? How to calculate average of array in Java? What is Array in Java? write a java program to find the summation of all the integers entered on command line Sum of two numbers using command line arguments in Java How to create and use Array in Java? How to pass command line arguments in Java? How to create Applet Hello World? Appending String efficiently in Java How to append String in Java? How to list even numbers between 1 and 100? How to add BigDecimal in Java? What is Abstraction In Java? Which is best Beginners Java Tutorial? What is java.util package? Create list from array in Java Filter collection in Java 8 What is the best way to filter a Java Collection? Easy way to transform Collection to Array? How to convert Collection to Array in Java? What are Basic Java Language Elements? Advanced Java Tutorials in 2017 Java brief history Best Reasons to learn Java

Ads

 
Advertisement null

Ads