Package com.puppycrawl.tools.checkstyle.checks.whitespace

Class WhitespaceAroundCheck

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

Checks that a token is surrounded by whitespace. Empty constructor, method, class, enum, interface, loop bodies (blocks), lambdas of the form 

 public MyClass() {}      // empty constructor
 public void func() {}    // empty method
 public interface Foo {} // empty interface
 public class Foo {} // empty class
 public enum Foo {} // empty enum
 MyClass c = new MyClass() {}; // empty anonymous class
 while (i = 1) {} // empty while loop
 for (int i = 1; i > 1; i++) {} // empty for loop
 do {} while (i = 1); // empty do-while loop
 Runnable noop = () -> {}; // empty lambda
 public @interface Beta {} // empty annotation type

may optionally be exempted from the policy using the allowEmptyMethods, allowEmptyConstructors, allowEmptyTypes, allowEmptyLoops, allowEmptyLambdas and allowEmptyCatches properties.

This check does not flag as violation double brace initialization like: 

 new Properties() {{
     setProperty("key", "value");
 }};

Parameter allowEmptyCatches allows to suppress violations when token list contains SLIST to check if beginning of block is surrounded by whitespace and catch block is empty, for example: 

 try {
     k = 5 / i;
 } catch (ArithmeticException ex) {}

With this property turned off, this raises violation because the beginning of the catch block (left curly bracket) is not separated from the end of the catch block (right curly bracket).

To configure the check: 

 <module name="WhitespaceAround"/>

Example: 

 class Test {
     public Test(){} // 2 violations, '{' is not followed and preceded by whitespace.
     public static void main(String[] args) {
         if (foo) { // ok
             // body
         }
         else{ // violation
             // body
         }

         for (int i = 1; i > 1; i++) {} // violation, '{' is not followed by whitespace.

         Runnable noop = () ->{}; // 2 violations,
                                     // '{' is not followed and preceded by whitespace.
         try {
             // body
         } catch (Exception e){} // 2 violations,
                                 // '{' is not followed and preceded by whitespace.

         char[] vowels = {'a', 'e', 'i', 'o', 'u'};
         for (char item: vowels) { // ok, because ignoreEnhancedForColon is true by default
             // body
         }
     }
 }

To configure the check for whitespace only around assignment operators: 

 <module name="WhitespaceAround">
   <property name="tokens"
     value="ASSIGN,DIV_ASSIGN,PLUS_ASSIGN,MINUS_ASSIGN,STAR_ASSIGN,
            MOD_ASSIGN,SR_ASSIGN,BSR_ASSIGN,SL_ASSIGN,BXOR_ASSIGN,
            BOR_ASSIGN,BAND_ASSIGN"/>
 </module>

Example: 

 class Test {
     public static void main(String[] args) {
         int b=10; // violation
         int c = 10; // ok
         b+=10; // violation
         b += 10; // ok
         c*=10; // violation
         c *= 10; // ok
         c-=5; // violation
         c -= 5; // ok
         c/=2; // violation
         c /= 2; // ok
         c%=1; // violation
         c %= 1; // ok
         c>>=1; // violation
         c >>= 1; // ok
         c>>>=1; // violation
         c >>>= 1; // ok
     }
     public void myFunction() {
         c^=1; // violation
         c ^= 1; // ok
         c|=1; // violation
         c |= 1; // ok
         c&=1; // violation
         c &= 1; // ok
         c<<=1; // violation
         c <<= 1; // ok
     }
 }

To configure the check for whitespace only around curly braces: 

 <module name="WhitespaceAround">
   <property name="tokens" value="LCURLY,RCURLY"/>
 </module>

Example: 

 class Test {
     public void myFunction() {} // violation
     public void myFunction() { } // ok
 }

To configure the check to allow empty method bodies: 

 <module name="WhitespaceAround">
   <property name="allowEmptyMethods" value="true"/>
 </module>

Example: 

 class Test {
     public void muFunction() {} // ok
     int a=4; // 2 violations, '=' is not followed and preceded by whitespace.
 }

To configure the check to allow empty constructor bodies: 

 <module name="WhitespaceAround">
   <property name="allowEmptyConstructors" value="true"/>
 </module>

Example: 

 class Test {
     public Test() {} // ok
     public void muFunction() {} // violation, '{' is not followed by whitespace.
 }

To configure the check to allow empty type bodies: 

 <module name="WhitespaceAround">
   <property name="allowEmptyTypes" value="true"/>
 </module>

Example: 

 class Test {} // ok
 interface testInterface{} // ok
 class anotherTest {
     int a=4; // 2 violations, '=' is not followed and preceded by whitespace.
 }

To configure the check to allow empty loop bodies: 

 <module name="WhitespaceAround">
   <property name="allowEmptyLoops" value="true"/>
 </module>

Example: 

 class Test {
     public static void main(String[] args) {
         for (int i = 100;i > 10; i--){} // ok
         do {} while (i = 1); // ok
         int a=4; // 2 violations, '=' is not followed and preceded by whitespace.
     }
 }

To configure the check to allow empty lambda bodies: 

 <module name="WhitespaceAround">
   <property name="allowEmptyLambdas" value="true"/>
 </module>

Example: 

 class Test {
     public static void main(String[] args) {
         Runnable noop = () -> {}; // ok
         int a=4; // 2 violations, '=' is not followed and preceded by whitespace.
     }
 }

To configure the check to allow empty catch bodies: 

 <module name="WhitespaceAround">
   <property name="allowEmptyCatches" value="true"/>
 </module>

Example: 

 class Test {
     public static void main(String[] args) {
         int a=4; // 2 violations, '=' is not followed and preceded by whitespace.
         try {
             // body
         } catch (Exception e){} // ok
     }
 }

Also, this check can be configured to ignore the colon in an enhanced for loop. The colon in an enhanced for loop is ignored by default.

To configure the check to ignore the colon: 

 <module name="WhitespaceAround">
   <property name="ignoreEnhancedForColon" value="false" />
 </module>

Example: 

 class Test {
     public static void main(String[] args) {
         int a=4; // 2 violations , '=' is not followed and preceded by whitespace.
         char[] vowels = {'a', 'e', 'i', 'o', 'u'};
         for (char item: vowels) { // violation, ':' is not preceded by whitespace.
             // body
         }
     }
 }

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • ws.notFollowed
  • ws.notPreceded
Since:
3.0

  • Field Details

    • MSG_WS_NOT_PRECEDED

      public static final String MSG_WS_NOT_PRECEDED
      A key is pointing to the warning message text in "messages.properties" file.
      See Also:

    • MSG_WS_NOT_FOLLOWED

      public static final String MSG_WS_NOT_FOLLOWED
      A key is pointing to the warning message text in "messages.properties" file.
      See Also:

    • allowEmptyConstructors

      private boolean allowEmptyConstructors
      Allow empty constructor bodies.

    • allowEmptyMethods

      private boolean allowEmptyMethods
      Allow empty method bodies.

    • allowEmptyTypes

      private boolean allowEmptyTypes
      Allow empty class, interface and enum bodies.

    • allowEmptyLoops

      private boolean allowEmptyLoops
      Allow empty loop bodies.

    • allowEmptyLambdas

      private boolean allowEmptyLambdas
      Allow empty lambda bodies.

    • allowEmptyCatches

      private boolean allowEmptyCatches
      Allow empty catch bodies.

    • ignoreEnhancedForColon

      private boolean ignoreEnhancedForColon
      Ignore whitespace around colon in enhanced for loop.

  • Constructor Details

    • WhitespaceAroundCheck

      public WhitespaceAroundCheck()

  • 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:

    • setAllowEmptyMethods

      public void setAllowEmptyMethods(boolean allow)
      Setter to allow empty method bodies.
      Parameters:
      allow - true to allow empty method bodies.

    • setAllowEmptyConstructors

      public void setAllowEmptyConstructors(boolean allow)
      Setter to allow empty constructor bodies.
      Parameters:
      allow - true to allow empty constructor bodies.

    • setIgnoreEnhancedForColon

      public void setIgnoreEnhancedForColon(boolean ignore)
      Setter to ignore whitespace around colon in enhanced for loop.
      Parameters:
      ignore - true to ignore enhanced for colon.

    • setAllowEmptyTypes

      public void setAllowEmptyTypes(boolean allow)
      Setter to allow empty class, interface and enum bodies.
      Parameters:
      allow - true to allow empty type bodies.

    • setAllowEmptyLoops

      public void setAllowEmptyLoops(boolean allow)
      Setter to allow empty loop bodies.
      Parameters:
      allow - true to allow empty loops bodies.

    • setAllowEmptyLambdas

      public void setAllowEmptyLambdas(boolean allow)
      Setter to allow empty lambda bodies.
      Parameters:
      allow - true to allow empty lambda expressions.

    • setAllowEmptyCatches

      public void setAllowEmptyCatches(boolean allow)
      Setter to allow empty catch bodies.
      Parameters:
      allow - true to allow empty catch blocks.

    • 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

    • isNotRelevantSituation

      private boolean isNotRelevantSituation(DetailAST ast, int currentType)
      Is ast not a target of Check.
      Parameters:
      ast - ast
      currentType - type of ast
      Returns:
      true is ok to skip validation

    • shouldCheckSeparationFromPreviousToken

      private static boolean shouldCheckSeparationFromPreviousToken(DetailAST ast)
      Check if it should be checked if previous token is separated from current by whitespace. This function is needed to recognise double brace initialization as valid, unfortunately its not possible to implement this functionality in isNotRelevantSituation method, because in this method when we return true(is not relevant) ast is later doesn't check at all. For example: new Properties() {{setProperty("double curly braces", "are not a style violation"); }}; For second left curly brace in first line when we would return true from isNotRelevantSituation it wouldn't later check that the next token(setProperty) is not separated from previous token.
      Parameters:
      ast - current AST.
      Returns:
      true if it should be checked if previous token is separated by whitespace, false otherwise.

    • shouldCheckSeparationFromNextToken

      private boolean shouldCheckSeparationFromNextToken(DetailAST ast, char nextChar)
      Check if it should be checked if next token is separated from current by whitespace. Explanation why this method is needed is identical to one included in shouldCheckSeparationFromPreviousToken method.
      Parameters:
      ast - current AST.
      nextChar - next character.
      Returns:
      true if it should be checked if next token is separated by whitespace, false otherwise.

    • isAnonymousInnerClassEnd

      private static boolean isAnonymousInnerClassEnd(int currentType, char nextChar)
      Check for "})" or "};" or "},". Happens with anon-inners
      Parameters:
      currentType - token
      nextChar - next symbol
      Returns:
      true is that is end of anon inner class

    • isEmptyBlock

      private boolean isEmptyBlock(DetailAST ast, int parentType)
      Is empty block.
      Parameters:
      ast - ast
      parentType - parent
      Returns:
      true is block is empty

    • isEmptyBlock

      private static boolean isEmptyBlock(DetailAST ast, int parentType, int match)
      Tests if a given DetailAST is part of an empty block. An example empty block might look like the following 
         public void myMethod(int val) {}
      In the above, the method body is an empty block ("{}").
      Parameters:
      ast - the DetailAST to test.
      parentType - the token type of ast's parent.
      match - the parent token type we're looking to match.
      Returns:
      true if ast makes up part of an empty block contained under a match token type node.

    • isColonOfCaseOrDefault

      private static boolean isColonOfCaseOrDefault(int parentType)
      Whether colon belongs to cases or defaults.
      Parameters:
      parentType - parent
      Returns:
      true if current token in colon of case or default tokens

    • isColonOfForEach

      private boolean isColonOfForEach(int parentType)
      Whether colon belongs to for-each.
      Parameters:
      parentType - parent
      Returns:
      true if current token in colon of for-each token

    • isArrayInitialization

      private static boolean isArrayInitialization(int currentType, int parentType)
      Is array initialization.
      Parameters:
      currentType - current token
      parentType - parent token
      Returns:
      true is current token inside array initialization

    • isEmptyMethodBlock

      private boolean isEmptyMethodBlock(DetailAST ast, int parentType)
      Test if the given DetailAST is part of an allowed empty method block.
      Parameters:
      ast - the DetailAST to test.
      parentType - the token type of ast's parent.
      Returns:
      true if ast makes up part of an allowed empty method block.

    • isEmptyCtorBlockCheckedFromRcurly

      private boolean isEmptyCtorBlockCheckedFromRcurly(DetailAST ast)
      Test if the given DetailAST is part of an allowed empty constructor (ctor) block checked from RCURLY.
      Parameters:
      ast - the DetailAST to test.
      Returns:
      true if ast makes up part of an allowed empty constructor block.

    • isEmptyCtorBlockCheckedFromSlist

      private boolean isEmptyCtorBlockCheckedFromSlist(DetailAST ast)
      Test if the given DetailAST is a part of an allowed empty constructor checked from SLIST token.
      Parameters:
      ast - the DetailAST to test.
      Returns:
      true if ast makes up part of an empty constructor block.

    • isEmptyLoop

      private boolean isEmptyLoop(DetailAST ast, int parentType)
      Checks if loop is empty.
      Parameters:
      ast - ast the DetailAST to test.
      parentType - the token type of ast's parent.
      Returns:
      true if ast makes up part of an allowed empty loop block.

    • isEmptyLambda

      private boolean isEmptyLambda(DetailAST ast, int parentType)
      Test if the given DetailAST is part of an allowed empty lambda block.
      Parameters:
      ast - the DetailAST to test.
      parentType - the token type of ast's parent.
      Returns:
      true if ast makes up part of an allowed empty lambda block.

    • isEmptyCatch

      private boolean isEmptyCatch(DetailAST ast, int parentType)
      Tests if the given DetailAst is part of an allowed empty catch block.
      Parameters:
      ast - the DetailAst to test.
      parentType - the token type of ast's parent
      Returns:
      true if ast makes up part of an allowed empty catch block.

    • isEmptyType

      private static boolean isEmptyType(DetailAST ast)
      Test if the given DetailAST is part of an empty block. An example empty block might look like the following 
         class Foo {}
      Parameters:
      ast - ast the DetailAST to test.
      Returns:
      true if ast makes up part of an empty block contained under a match token type node.

    • isPartOfDoubleBraceInitializerForPreviousToken

      private static boolean isPartOfDoubleBraceInitializerForPreviousToken(DetailAST ast)
      Check if given ast is part of double brace initializer and if it should omit checking if previous token is separated by whitespace.
      Parameters:
      ast - ast to check
      Returns:
      true if it should omit checking for previous token, false otherwise

    • isPartOfDoubleBraceInitializerForNextToken

      private static boolean isPartOfDoubleBraceInitializerForNextToken(DetailAST ast)
      Check if given ast is part of double brace initializer and if it should omit checking if next token is separated by whitespace. See PR#2845 for more information why this function was needed.
      Parameters:
      ast - ast to check
      Returns:
      true if it should omit checking for next token, false otherwise