Java Coding Standards

Sun estimates that on a typical lifetime of codes, creation and testing of codes consumes only 20%, and the remaining 80% efforts will go to maintenance and enhancement. Also, hardly any software is maintained for its whole life is maintained by its author. Thus, Sun set standard convention that they follow and encourage other Java programmers to improve readability of the codes of software, allowing programmers to understand new code easily (that others have written),  and reduce the effort focused on testing, maintaining and enhancement of any piece of code.

1. Classes and Interfaces
   Classes names should be nouns.  For one worded classes, first letters should be capitalized. If two or more words are linked together to form the name, the first letter of the succeeding words should be capitalized (Billing + File = BillingFile).
   Examples:
   

    Header  
    Details  
    Flowers  
    BillingFile  
   

   For Interfaces, names should be adjectives.

    Serializable  
    Runnable  
   



2. Methods
   Method names should be in verb-noun combination. Format should be in camel case (camelCase) where first word should be in lower case and the first letter of the succeeding word/s should be in capital.
   Examples:

   Header  
   getSum
   convertFile
   formatNumber
   computeBillingAmount 
   



3. Variables should also be in camelCase
   Examples:

   frameHeight
   billSummary
   accountName
   temp
   



4. Constants - Java constants are variables marked as static and final. They should be named in uppercase with underscore as separators.
   Examples:

   ENCRYPT_KEY
   MIN_WIDTH
   MAX_HEIGHT
   ITERATOR 

Source: Java Code Convention, Sun Certified Programmer for Java 6 Study Guide by Kathy Sierra and Bert Bates