Package com.puppycrawl.tools.checkstyle.checks.coding

Class ExplicitInitializationCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class ExplicitInitializationCheck
extends AbstractCheck

    Checks if any class or object member is explicitly initialized to default for its type value (null for object references, zero for numeric types and char and false for boolean.

    Rationale: Each instance variable gets initialized twice, to the same value. Java initializes each instance variable to its default value (0 or null) before performing any initialization specified in the code. So there is a minor inefficiency.

    • Property onlyObjectReferences - control whether only explicit initializations made to null for objects should be checked. Default value is false.

    To configure the check: 

     <module name="ExplicitInitialization"/>

    To configure the check so that it only checks for objects that explicitly initialize to null: 

     <module name="ExplicitInitialization">
   <property name="onlyObjectReferences" value="true"/>
 </module>

    Example: 

     public class Test {
   private int a = 0;
   private int b = 1;
   private int c = 2;

   private boolean a = true;
   private boolean b = false;
   private boolean c = true;
   private boolean d = false;
   private boolean e = false;

   private A a = new A();
   private A b = null; // violation
   private C c = null; // violation
   private D d = new D();

   int ar1[] = null; // violation
   int ar2[] = new int[];
   int ar3[];
   private Bar<String> bar = null; // violation
   private Bar<String>[] barArray = null; // violation

   public static void main( String [] args ) {
   }
 }
    Since:
    3.2

    • 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

    • Constructor Detail

      • ExplicitInitializationCheck

        public ExplicitInitializationCheck()

    • Method Detail

      • getDefaultTokens

        public final 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

      • getRequiredTokens

        public final 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

      • getAcceptableTokens

        public final 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

      • setOnlyObjectReferences

        public void setOnlyObjectReferences​(boolean onlyObjectReferences)
        Setter to control whether only explicit initializations made to null for objects should be checked.
        Parameters:
        onlyObjectReferences - whether only explicit initialization made to null should be checked