com.puppycrawl.tools.checkstyle.checks.imports

Class RedundantImportCheck

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.RedundantImportCheck

All Implemented Interfaces:

Configurable, Contextualizable

public class RedundantImportCheck
extends AbstractCheck

Checks for redundant import statements. An import statement is considered redundant if:

• It is a duplicate of another import. This is, when a class is imported more than once.
• The class non-statically imported is from the java.lang package, e.g. importing java.lang.String.
• The class non-statically imported is from the same package as the current package.

To configure the check:

 <module name="RedundantImport"/>
 

Example:

 package Test;
 import static Test.MyClass.*; // OK, static import
 import static java.lang.Integer.MAX_VALUE; // OK, static import

 import Test.MyClass; // violation, imported from the same package as the current package
 import java.lang.String; // violation, the class imported is from the 'java.lang' package
 import java.util.Scanner; // OK
 import java.util.Scanner; // violation, it is a duplicate of another import
 public class MyClass{ };
 

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• import.duplicate
• import.lang
• import.same

Since:

3.0

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.util.Set<FullIdent>	imports Set of the imports.
static java.lang.String	MSG_DUPLICATE A key is pointing to the warning message text in "messages.properties" file.
static java.lang.String	MSG_LANG A key is pointing to the warning message text in "messages.properties" file.
static java.lang.String	MSG_SAME A key is pointing to the warning message text in "messages.properties" file.
private java.lang.String	pkgName Name of package in file.
private java.util.Set<FullIdent>	staticImports Set of static imports.

Constructor Summary

Constructors

Constructor and Description
RedundantImportCheck()

Method Summary

Modifier and Type	Method and Description
void	beginTree(DetailAST aRootAST) Called before the starting to process a tree.
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 static boolean	isFromPackage(java.lang.String importName, java.lang.String pkg) Determines if an import statement is for types from a specified package.
void	visitToken(DetailAST ast) Called to process a token.

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

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_LANG

public static final java.lang.String MSG_LANG

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

See Also:

Constant Field Values

MSG_SAME

public static final java.lang.String MSG_SAME

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

See Also:

Constant Field Values

MSG_DUPLICATE

public static final java.lang.String MSG_DUPLICATE

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

See Also:

Constant Field Values

imports

private final java.util.Set<FullIdent> imports

Set of the imports.

staticImports

private final java.util.Set<FullIdent> staticImports

Set of static imports.

pkgName

private java.lang.String pkgName

Name of package in file.

Constructor Detail

RedundantImportCheck

public RedundantImportCheck()

Method Detail

beginTree

public void beginTree(DetailAST aRootAST)

Description copied from class: AbstractCheck

Called before the starting to process a tree. Ideal place to initialize information that is to be collected whilst processing a tree.

Overrides:

beginTree in class AbstractCheck

Parameters:

aRootAST - the root of the tree

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

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

isFromPackage

private static boolean isFromPackage(java.lang.String importName,
                                     java.lang.String pkg)

Determines if an import statement is for types from a specified package.

Parameters:

importName - the import name

pkg - the package name

Returns:

whether from the package