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
static String	MSG_WS_FOLLOWED A key is pointing to the warning message text in "messages.properties" file.
static String	MSG_WS_ILLEGAL_FOLLOW A key is pointing to the warning message text in "messages.properties" file.
static String	MSG_WS_NOT_PRECEDED A key is pointing to the warning message text in "messages.properties" file.
static String	MSG_WS_PRECEDED A key is pointing to the warning message text in "messages.properties" file.

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.
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.
void	visitToken(DetailAST ast) Called to process a token.

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

clearMessages, destroy, finishTree, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, 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 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 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 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 String MSG_WS_ILLEGAL_FOLLOW

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

See Also:

Constant Field Values

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