Class AvoidStaticImportCheck

java.lang.Object
com.puppycrawl.tools.checkstyle.api.AutomaticBean
com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
com.puppycrawl.tools.checkstyle.api.AbstractCheck
com.puppycrawl.tools.checkstyle.checks.imports.AvoidStaticImportCheck
All Implemented Interfaces:
Configurable, Contextualizable
public class AvoidStaticImportCheck extends AbstractCheck

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).

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, ....

  • Property 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. Type is java.lang.String[]. Default value is "".

To configure the check: 

<module name="AvoidStaticImport"/>

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

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • import.avoidStatic
Since:
5.0

  • Field Details

    • MSG_KEY

      public static final String MSG_KEY
      A key is pointing to the warning message text in "messages.properties" file.
      See Also:

    • excludes

      private String[] 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.

  • Constructor Details

    • AvoidStaticImportCheck

      public AvoidStaticImportCheck()

  • Method Details

    • getDefaultTokens

      public int[] getDefaultTokens()
      Description copied from class: AbstractCheck
      Returns the default token a check is interested in. Only used if the configuration for a check does not define the tokens.
      Specified by:
      getDefaultTokens in class AbstractCheck
      Returns:
      the default tokens
      See Also:

    • getAcceptableTokens

      public int[] getAcceptableTokens()
      Description copied from class: AbstractCheck
      The configurable token set. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check's default tokens.
      Specified by:
      getAcceptableTokens in class AbstractCheck
      Returns:
      the token set this check is designed for.
      See Also:

    • getRequiredTokens

      public int[] getRequiredTokens()
      Description copied from class: AbstractCheck
      The tokens that this check must be registered for.
      Specified by:
      getRequiredTokens in class AbstractCheck
      Returns:
      the token set this must be registered for.
      See Also:

    • setExcludes

      public void setExcludes(String... excludes)
      Setter to 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.
      Parameters:
      excludes - a list of fully-qualified class names/specific static members where static imports are ok

    • visitToken

      public void visitToken(DetailAST ast)
      Description copied from class: AbstractCheck
      Called to process a token.
      Overrides:
      visitToken in class AbstractCheck
      Parameters:
      ast - the token to process

    • isExempt

      private boolean isExempt(String classOrStaticMember)
      Checks if a class or static member is exempt from known excludes.
      Parameters:
      classOrStaticMember - the class or static member
      Returns:
      true if except false if not

    • isStarImportOfPackage

      private static boolean isStarImportOfPackage(String classOrStaticMember, String exclude)
      Returns true if classOrStaticMember is a starred name of package, not just member name.
      Parameters:
      classOrStaticMember - - full name of member
      exclude - - current exclusion
      Returns:
      true if member in exclusion list