com.puppycrawl.tools.checkstyle.checks.whitespace

Class GenericWhitespaceCheck

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.GenericWhitespaceCheck

All Implemented Interfaces:

Configurable, Contextualizable

public class GenericWhitespaceCheck
extends AbstractCheck

Checks that the whitespace around the Generic tokens (angle brackets) "<" and ">" are correct to the typical convention. The convention is not configurable.

Left angle bracket ("<"):

• should be preceded with whitespace only in generic methods definitions.
• should not be preceded with whitespace when it is precede method name or constructor.
• should not be preceded with whitespace when following type name.
• should not be followed with whitespace in all cases.

Right angle bracket (">"):

• should not be preceded with whitespace in all cases.
• should be followed with whitespace in almost all cases, except diamond operators and when preceding method name or constructor.

To configure the check:

 <module name="GenericWhitespace"/>
 

Examples with correct spacing:

 // Generic methods definitions
 public void <K, V extends Number> boolean foo(K, V) {}
 // Generic type definition
 class name<T1, T2, ..., Tn> {}
 // Generic type reference
 OrderedPair<String, Box<Integer>> p;
 // Generic preceded method name
 boolean same = Util.<Integer, String>compare(p1, p2);
 // Diamond operator
 Pair<Integer, String> p1 = new Pair<>(1, "apple");
 // Method reference
 List<T> list = ImmutableList.Builder<T>::new;
 // Method reference
 sort(list, Comparable::<String>compareTo);
 // Constructor call
 MyClass obj = new <String>MyClass();
 

Examples with incorrect spacing:

 List< String> l; // violation, "<" followed by whitespace
 Box b = Box. <String>of("foo"); // violation, "<" preceded with whitespace
 public<T> void foo() {} // violation, "<" not preceded with whitespace

 List a = new ArrayList<> (); // violation, ">" followed by whitespace
 Map<Integer, String>m; // violation, ">" not followed by whitespace
 Pair<Integer, Integer > p; // violation, ">" preceded with whitespace
 

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• ws.followed
• ws.illegalFollow
• ws.notPreceded
• ws.preceded

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 static java.lang.String	CLOSE_ANGLE_BRACKET Close angle bracket literal.
private int	depth Used to count the depth of a Generic expression.
static java.lang.String	MSG_WS_FOLLOWED A key is pointing to the warning message text in "messages.properties" file.
static java.lang.String	MSG_WS_ILLEGAL_FOLLOW A key is pointing to the warning message text in "messages.properties" file.
static java.lang.String	MSG_WS_NOT_PRECEDED A key is pointing to the warning message text in "messages.properties" file.
static java.lang.String	MSG_WS_PRECEDED A key is pointing to the warning message text in "messages.properties" file.
private static java.lang.String	OPEN_ANGLE_BRACKET Open angle bracket literal.

Constructor Summary

Constructors

Constructor and Description
GenericWhitespaceCheck()

Method Summary

Modifier and Type	Method and Description
void	beginTree(DetailAST rootAST) Called before the starting to process a tree.
private static boolean	containsWhitespaceBefore(int before, java.lang.String line) Returns whether the specified string contains only whitespace up to specified index.
private static boolean	containsWhitespaceBetween(int fromIndex, int toIndex, java.lang.String line) Returns whether the specified string contains only whitespace between specified indices.
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	isAfterMethodReference(DetailAST genericEnd) Checks if current generic end ('>') is located after method reference operator.
private static boolean	isCharacterValidAfterGenericEnd(char charAfter) Checks whether given character is valid to be right after generic ends.
private static boolean	isGenericBeforeCtor(DetailAST ast) Checks if generic is before constructor invocation.
private static boolean	isGenericBeforeMethod(DetailAST ast) Is generic before method reference.
private void	processEnd(DetailAST ast) Checks the token for the end of Generics.
private void	processNestedGenerics(DetailAST ast, java.lang.String line, int after) Process Nested generics.
private void	processSingleGeneric(DetailAST ast, java.lang.String line, int after) Process Single-generic.
private void	processStart(DetailAST ast) Checks the token for the start of Generics.
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_WS_PRECEDED

public static final java.lang.String MSG_WS_PRECEDED

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

See Also:

Constant Field Values

MSG_WS_FOLLOWED

public static final java.lang.String MSG_WS_FOLLOWED

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

See Also:

Constant Field Values

MSG_WS_NOT_PRECEDED

public static final java.lang.String MSG_WS_NOT_PRECEDED

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

See Also:

Constant Field Values

MSG_WS_ILLEGAL_FOLLOW

public static final java.lang.String MSG_WS_ILLEGAL_FOLLOW

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

See Also:

Constant Field Values

OPEN_ANGLE_BRACKET

private static final java.lang.String OPEN_ANGLE_BRACKET

Open angle bracket literal.

See Also:

Constant Field Values

CLOSE_ANGLE_BRACKET

private static final java.lang.String CLOSE_ANGLE_BRACKET

Close angle bracket literal.

See Also:

Constant Field Values

depth

private int depth

Used to count the depth of a Generic expression.

Constructor Detail

GenericWhitespaceCheck

public GenericWhitespaceCheck()

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

beginTree

public void beginTree(DetailAST rootAST)

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:

rootAST - the root of the tree

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

processEnd

private void processEnd(DetailAST ast)

Checks the token for the end of Generics.

Parameters:

ast - the token to check

processNestedGenerics

private void processNestedGenerics(DetailAST ast,
                                   java.lang.String line,
                                   int after)

Process Nested generics.

Parameters:

ast - token

line - line content

after - position after

processSingleGeneric

private void processSingleGeneric(DetailAST ast,
                                  java.lang.String line,
                                  int after)

Process Single-generic.

Parameters:

ast - token

line - line content

after - position after

isGenericBeforeCtor

private static boolean isGenericBeforeCtor(DetailAST ast)

Checks if generic is before constructor invocation.

Parameters:

ast - ast

Returns:

true if generic before a constructor invocation

isGenericBeforeMethod

private static boolean isGenericBeforeMethod(DetailAST ast)

Is generic before method reference.

Parameters:

ast - ast

Returns:

true if generic before a method ref

isAfterMethodReference

private static boolean isAfterMethodReference(DetailAST genericEnd)

Checks if current generic end ('>') is located after method reference operator.

Parameters:

genericEnd - TokenTypes.GENERIC_END

Returns:

true if '>' follows after method reference.

processStart

private void processStart(DetailAST ast)

Checks the token for the start of Generics.

Parameters:

ast - the token to check

containsWhitespaceBetween

private static boolean containsWhitespaceBetween(int fromIndex,
                                                 int toIndex,
                                                 java.lang.String line)

Returns whether the specified string contains only whitespace between specified indices.

Parameters:

fromIndex - the index to start the search from. Inclusive

toIndex - the index to finish the search. Exclusive

line - the line to check

Returns:

whether there are only whitespaces (or nothing)

containsWhitespaceBefore

private static boolean containsWhitespaceBefore(int before,
                                                java.lang.String line)

Returns whether the specified string contains only whitespace up to specified index.

Parameters:

before - the index to start the search from. Inclusive

line - the index to finish the search. Exclusive

Returns:

true if there are only whitespaces, false if there is nothing before or some other characters

isCharacterValidAfterGenericEnd

private static boolean isCharacterValidAfterGenericEnd(char charAfter)

Checks whether given character is valid to be right after generic ends.

Parameters:

charAfter - character to check

Returns:

checks if given character is valid