Package com.puppycrawl.tools.checkstyle.checks.imports

Class AvoidStarImportCheck

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.AvoidStarImportCheck
All Implemented Interfaces:
Configurable, Contextualizable
public class AvoidStarImportCheck extends AbstractCheck

Checks that there are no import statements that use the * notation.

Rationale: Importing all classes from a package or static members from a class leads to tight coupling between packages or classes and might lead to problems when a new version of a library introduces name clashes.

Note that property excludes is not recursive, subpackages of excluded packages are not automatically excluded.

  • Property excludes - Specify packages where star imports are allowed. Type is java.lang.String[]. Default value is "".
  • Property allowClassImports - Control whether to allow starred class imports like import java.util.*;. Type is boolean. Default value is false.
  • Property allowStaticMemberImports - Control whether to allow starred static member imports like import static org.junit.Assert.*;. Type is boolean. Default value is false.

To configure the check: 

 <module name="AvoidStarImport"/>

Example:

 import java.util.Scanner;         // OK
 import java.io.*;                 // violation
 import static java.lang.Math.*;   // violation
 import java.util.*;               // violation
 import java.net.*;                // violation

To configure the check so that star imports from packages java.io and java.net as well as static members from class java.lang.Math are allowed: 

 <module name="AvoidStarImport">
   <property name="excludes" value="java.io,java.net,java.lang.Math"/>
 </module>

Example:

 import java.util.Scanner;         // OK
 import java.io.*;                 // OK
 import static java.lang.Math.*;   // OK
 import java.util.*;               // violation
 import java.net.*;                // OK

To configure the check so that star imports from all packages are allowed: 

 <module name="AvoidStarImport">
   <property name="allowClassImports" value="true"/>
 </module>

Example:

 import java.util.Scanner;         // OK
 import java.io.*;                 // OK
 import static java.lang.Math.*;   // violation
 import java.util.*;               // OK
 import java.net.*;                // OK

To configure the check so that starred static member imports from all packages are allowed: 

 <module name="AvoidStarImport">
   <property name="allowStaticMemberImports" value="true"/>
 </module>

Example:

 import java.util.Scanner;         // OK
 import java.io.*;                 // violation
 import static java.lang.Math.*;   // OK
 import java.util.*;               // violation
 import java.net.*;                // violation

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • import.avoidStar
Since:
3.0

  • 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:

    • STAR_IMPORT_SUFFIX

      private static final String STAR_IMPORT_SUFFIX
      Suffix for the star import.
      See Also:

    • excludes

      private final List<String> excludes
      Specify packages where star imports are allowed.

    • allowClassImports

      private boolean allowClassImports
      Control whether to allow starred class imports like import java.util.*;.

    • allowStaticMemberImports

      private boolean allowStaticMemberImports
      Control whether to allow starred static member imports like import static org.junit.Assert.*;.

  • Constructor Details

    • AvoidStarImportCheck

      public AvoidStarImportCheck()

  • 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... excludesParam)
      Setter to specify packages where star imports are allowed.
      Parameters:
      excludesParam - a list of package names/fully-qualifies class names where star imports are ok.

    • setAllowClassImports

      public void setAllowClassImports(boolean allow)
      Setter to control whether to allow starred class imports like import java.util.*;.
      Parameters:
      allow - true to allow false to disallow

    • setAllowStaticMemberImports

      public void setAllowStaticMemberImports(boolean allow)
      Setter to control whether to allow starred static member imports like import static org.junit.Assert.*;.
      Parameters:
      allow - true to allow false to disallow

    • 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

    • logsStarredImportViolation

      private void logsStarredImportViolation(DetailAST startingDot)
      Gets the full import identifier. If the import is a starred import and it's not excluded then a violation is logged.
      Parameters:
      startingDot - the starting dot for the import statement