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

Class 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

    • 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

      • pkgName

        private java.lang.String pkgName
        Name of package in file.

    • 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

      • 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

      • 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