AvoidStaticImport

Since Checkstyle 5.0

Description

Checks that there are no static import statements.

Rationale: Importing static members can lead to naming conflicts between class' members. It may lead to poor code readability since it may no longer be clear what class a member resides in (without looking at the import statement).

Notes

If you exclude a starred import on a class this automatically excludes each member individually.

For example: Excluding java.lang.Math.*. will allow the import of each static member in the Math class individually like java.lang.Math.PI, java.lang.Math.cos, ....

Properties

name description type default value since
excludes Control whether to allow for certain classes via a star notation to be excluded such as java.lang.Math.* or specific static members to be excluded like java.lang.System.out for a variable or java.lang.Math.random for a method. See notes section for details. String[] {} 5.0

Examples

To configure the check: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidStaticImport"/>
  </module>
</module>

Example: 

import static java.lang.Math.pow;          // violation
import static java.lang.System.*;          // violation
import java.io.File;                       // OK
import java.util.*;                        // OK

To configure the check so that the java.lang.System.out member and all members from java.lang.Math are allowed: 

<module name="Checker">
  <module name="TreeWalker">
    <module name="AvoidStaticImport">
      <property name="excludes" value="java.lang.System.out,java.lang.Math.*"/>
    </module>
  </module>
</module>

Example: 

import static java.lang.Math.*;            // OK
import static java.lang.System.out;        // OK
import static java.lang.Integer.parseInt;  // violation
import java.io.*;                          // OK
import java.util.*;                        // OK

Example of Usage

Violation Messages

All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.

Package

com.puppycrawl.tools.checkstyle.checks.imports

Parent Module

TreeWalker