Since Checkstyle 3.0
Checks that package names conform to a specified pattern.
The default value of format
for module PackageName
has been
chosen to match the requirements in the
Java
Language specification and the Sun coding conventions. However,
both underscores and uppercase letters are rather uncommon, so most
configurations should probably assign value ^[a-z]+(\.[a-z][a-z0-9]*)*$
to
format
for module PackageName
.
name | description | type | default value | since |
---|---|---|---|---|
format | Control the pattern to match valid identifiers. | Pattern | "^[a-z]+(\.[a-zA-Z_]\w*)*$" |
3.0 |
To configure the check:
<module name="Checker"> <module name="TreeWalker"> <module name="PackageName"/> </module> </module>
Code Example:
package com; // OK package COM; // violation, name 'COM' must match pattern '^[a-z]+(\.[a-zA-Z_]\w*)*$' package com.checkstyle.checks; // OK package com.A.checkstyle.checks; // OK package com.checkstyle1.checks; // OK package com.checkSTYLE.checks; // OK package com._checkstyle.checks_; // OK
An example of how to configure the check to ensure with packages start with a lowercase letter and only contains lowercase letters or numbers is:
<module name="Checker"> <module name="TreeWalker"> <module name="PackageName"> <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/> </module> </module> </module>
Code Example:
package com; // OK package COM; // violation, name 'COM' must match pattern '^[a-z]+(\.[a-z][a-z0-9]*)*$' package com.checkstyle.checks; // OK package com.A.checkstyle.checks; // violation, name 'com.A.checkstyle' must match // pattern '^[a-z]+(\.[a-z][a-z0-9]*)*$' package com.checkstyle1.checks; // OK package com.checkSTYLE.checks; // violation, name 'com.checkSTYLE.checks' must // match pattern '^[a-z]+(\.[a-z][a-z0-9]*)*$' package com._checkstyle.checks_; // violation, name 'com._checkstyle.checks_' must match // pattern '^[a-z]+(\.[a-z][a-z0-9]*)*$'
All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.
com.puppycrawl.tools.checkstyle.checks.naming