Identifiers

Java offers the following conventions for writing identifiers. See the Java Code Conventions. 

Characters

An identifier begins with a letter, an underscore or a currency symbol (e.g.  $ ). This initial letter can be followed by any number of letters, digits, underscores or currency symbols.

Packages

The prefix of a unique package name is written in all-lowercase ASCII letters and should be one of the top-level domain names. Subsequent components of the package name vary according to an organization's own internal naming conventions. 

package: com.sun.eng

Classes and Interfaces

Classes and interfaces should be nouns, in mixed case with the first letter of each internal word capitalized. 

class: Clock
class: ImageSprite
interface: Storing

Methods

Methods should be verbs, in mixed case with the first letter lowercase, with the first letter of each internal word capitalized

i: run  ( -- )
i: runFast  ( -- )
: getBackground  ( -- )

Variables

Variables are written in mixed case with a lowercase first letter. Variable names should not start with underscore _ or dollar sign $ characters, even though both are allowed.

Standard types are written in lower case. Class types are written like classes, the first letter is capitalized.

int i
float frameWidth
Clock myClock

Constants

The names of constants should be all uppercase with words separated by underscores. 

static final int MIN_WIDTH