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Easy Learn Java: Programming Articles, Examples and Tips - Page 167


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The Java Lesson 3: Identifiers and primitive data types

Go to all tips in Java Lessons by Jon Huhtala
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1. Identifiers in Java | 2. Primitive data types in Java

Identifiers and primitive data types

Uses of identifiers

  • To name a variable (a data area that takes on different values during processing)

  • To name a method (a module of code)

  • To name a class (a definition from which objects can be constructed)

  • To label a statement (for later referencing)

Rules for identifiers

  • It must not be a Java keyword

  • It must begin with a letter, dollar sign ( $ ), or underscore ( _ )

  • Subsequent characters may be letters, dollar signs, underscores, or digits

  • Case matters. For example, the three identifiers MAIN, Main, and main are different.

Examples of valid identifiers

yearlyGrossPay

_2002_Budget

JuneActual

$totalAmtDue

Programming conventions

  • Are not enforced by the compiler but make it easier to read and maintain Java code

  • Most programmers use "camel caps" (such as firstQuarterSalesTotal) to handle long identifiers that appear to contain multiple words. Some use undercores (like first_Quarter_Sales_Totals).

  • Begin variable names, method names, and labels with a lower case letter. For example, totalAmount, hoursWorked, employeeName, calcBonus, and main.

  • Begin class names with a capital letter. For example, Person, Customer, SalesRep, and Part.

  • Names of constants should be all capitals. For example, TAX_RATE, COMMISSION, and DEPOSIT_CODE.



16 comments | Printer Friendly Page  Send to a Friend | Score: 4
Posted by jalex on Wednesday, February 11, 2004 (00:00:00) (23053 reads)

With 1.3.1 we got 4GB heaps on Solaris, why can't I get this to work on Windows?

Go to all tips in General Java

Question: With 1.3.1 we got 4GB heaps on Solaris, why can't I get this to work on Windows?

Answer: It's due to fragmentation of the address space. After Windows has loaded all its stuff, plus the java dlls, the largest available continuous chunk of addresses for the heap is about 1.4-1.6G on Win/NT. Might be smaller on Win/98.

If you really need more space they can try rebasing java.exe and the JDK dlls higher. But that won't buy you much (maybe a couple hundred meg).
from the Java Hotspot Virtual Machine FAQ:
http://java.sun.com/docs/hotspot/PerformanceFAQ.html

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Our older tips: March 22, 2001 - October 21, 2002 READ HERE
All published and not published on the site tips read HERE



4 comments | Printer Friendly Page  Send to a Friend | Score: 0
Posted by jalex on Wednesday, February 11, 2004 (00:00:00) (2661 reads)

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