com.puppycrawl.tools.checkstyle.checks.imports

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

Nested Class Summary

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

AutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field and Description
private java.lang.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.
static java.lang.String	MSG_KEY A key is pointing to the warning message text in "messages.properties" file.

Constructor Summary

Constructors

Constructor and Description
AvoidStaticImportCheck()

Method Summary

Modifier and Type	Method and Description
int[]	getAcceptableTokens() The configurable token set.
int[]	getDefaultTokens() Returns the default token a check is interested in.
int[]	getRequiredTokens() The tokens that this check must be registered for.
private boolean	isExempt(java.lang.String classOrStaticMember) Checks if a class or static member is exempt from known excludes.
private static boolean	isStarImportOfPackage(java.lang.String classOrStaticMember, java.lang.String exclude) Returns true if classOrStaticMember is a starred name of package, not just member name.
void	setExcludes(java.lang.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.
void	visitToken(DetailAST ast) Called to process a token.

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck

beginTree, clearViolations, destroy, finishTree, getFileContents, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, init, isCommentNodesRequired, leaveToken, log, log, log, setFileContents, setTabWidth, setTokens

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MSG_KEY

public static final java.lang.String MSG_KEY

A key is pointing to the warning message text in "messages.properties" file.

See Also:

Constant Field Values

excludes

private java.lang.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 Detail

AvoidStaticImportCheck

public AvoidStaticImportCheck()

Method Detail

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:

TokenTypes

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:

TokenTypes

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:

TokenTypes

setExcludes

public void setExcludes(java.lang.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(java.lang.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(java.lang.String classOrStaticMember,
                                             java.lang.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