Naming a Package
With programmers worldwide writing classes and interfaces using the Java programming language, it is likely that many programmers will use the same name for different types. In fact, the previous example does just that: It defines a Rectangle class when there is already a Rectangle class in the java.awt package. Still, the compiler allows both classes to have the same name if they are in different packages. The fully qualified name of each Rectangle class includes the package name. That is, the fully qualified name of the Rectangle class in the graphics package is graphics.Rectangle , and the fully qualified name of the Rectangle class in the java.awt package is java.awt.Rectangle .
This works well unless two independent programmers use the same name for their packages. What prevents this problem? Convention.
Naming Conventions
Package names are written in all lower case to avoid conflict with the names of classes or interfaces.
Companies use their reversed Internet domain name to begin their package namesfor example, com.example.mypackage for a package named mypackage created by a programmer at example.com .
Name collisions that occur within a single company need to be handled by convention within that company, perhaps by including the region or the project name after the company name (for example, com.example.region.mypackage ).
Packages in the Java language itself begin with java. or javax.
In some cases, the internet domain name may not be a valid package name. This can occur if the domain name contains a hyphen or other special character, if the package name begins with a digit or other character that is illegal to use as the beginning of a Java name, or if the package name contains a reserved Java keyword, such as «int». In this event, the suggested convention is to add an underscore. For example:
| Domain Name | Package Name Prefix |
|---|---|
| hyphenated-name.example.org | org.example.hyphenated_name |
| example.int | int_.example |
| 123name.example.com | com.example._123name |
Java Naming Conventions
Java naming conventions are sort of guidelines that application programmers are expected to follow to produce consistent and readable code throughout the application. If teams do not follow these conventions, they may collectively write an application code that is hard to read and difficult to understand.
Java heavily uses Camel Case notations for naming the methods, variables etc. and TitleCase notations for classes and interfaces.
Let’s understand these naming conventions in detail with examples.
Package names must be a group of words starting with all lowercase domain names (e.g. com, org, net, etc). Subsequent parts of the package name may be different according to an organization’s own internal naming conventions.
package com.howtodoinjava.webapp.controller; package com.company.myapplication.web.controller; package com.google.search.common;In Java, class names generally should be nouns, in title-case with the first letter of each separate word capitalized. e.g.
public class ArrayList <> public class Employee <> public class Record <> public class Identity <>In Java, interfaces names, generally, should be adjectives. Interfaces should be in the title case with the first letter of each separate word capitalized. In some cases, interfaces can be nouns as well when they present a family of classes e.g. List and Map .
public interface Serializable <> public interface Clonable <> public interface Iterable <> public interface List <>Methods always should be verbs. They represent action and the method name should clearly state the action they perform. The method name can be single or 2-3 words as needed to clearly represent the action. Words should be in camel case notation.
public Long getId() <> public void remove(Object o) <> public Object update(Object o) <> public Report getReportById(Long id) <> public Report getReportByName(String name) <>All instance, static and method parameter variable names should be in camel case notation. They should be short and enough to describe their purpose. Temporary variables can be a single character e.g. the counter in the loops.
public Long id; public EmployeeDao employeeDao; private Properties properties; for (int i = 0; i
6. Constant Naming Conventions
Java constants should be all UPPERCASE where words are separated by underscore character (“_”). Make sure to use the final modifier with constant variables.
public final String SECURITY_TOKEN = ". "; public final int INITIAL_SIZE = 16; public final Integer MAX_SIZE = Integer.MAX;Generic type parameter names should be uppercase single letters. The letter ‘T’ for type is typically recommended. In JDK classes, E is used for collection elements, S is used for service loaders, and K and V are used for map keys and values.
public interface Map <> public interface List extends Collection <> Iterator iterator() <>Similar to class constants, enumeration names should be all uppercase letters.
Annotation names follow title case notation. They can be adjectives, verbs, or nouns based on the requirements.
public @interface FunctionalInterface <> public @interface Deprecated <> public @interface Documented <> public @Async Documented
In this post, we discussed the naming conventions in Java to be followed for consistent writing of code which makes the code more readable and maintainable.
Naming conventions are probably the first best practice to follow while writing clean code in any programming language.