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

Class MissingSwitchDefaultCheck

java.lang.Object

com.puppycrawl.tools.checkstyle.AbstractAutomaticBean

com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

com.puppycrawl.tools.checkstyle.api.AbstractCheck

com.puppycrawl.tools.checkstyle.checks.coding.MissingSwitchDefaultCheck

All Implemented Interfaces:

Configurable, Contextualizable

public class MissingSwitchDefaultCheck
extends AbstractCheck

Checks that switch statement has a default clause.

Rationale: It's usually a good idea to introduce a default case in every switch statement. Even if the developer is sure that all currently possible cases are covered, this should be expressed in the default branch, e.g. by using an assertion. This way the code is protected against later changes, e.g. introduction of new types in an enumeration type.

This check does not validate any switch expressions. Rationale: The compiler requires switch expressions to be exhaustive. This means that all possible inputs must be covered.

This check does not validate switch statements that use pattern or null labels. Rationale: Switch statements that use pattern or null labels are checked by the compiler for exhaustiveness. This means that all possible inputs must be covered.

See the Java Language Specification for more information about switch statements and expressions.

See the Java Language Specification for more information about patterns.

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• missing.switch.default

Since:

3.1

Nested Class Summary

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean

AbstractAutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field	Description
static final String	MSG_KEY	A key is pointing to the warning message text in "messages.properties" file.
private static final Set<Integer>	SWITCH_STATEMENT_PARENTS	Represents the possible parent tokens of a switch statement.

Constructor Summary

Constructors

Constructor	Description
MissingSwitchDefaultCheck()

Method Summary

Modifier and Type	Method	Description
private static boolean	containsDefaultCaseLabelElement(DetailAST detailAst)	Checks if a switch block contains a default case label.
private static boolean	containsDefaultLabel(DetailAST detailAst)	Checks if the case group or its sibling contain the 'default' switch.
private static boolean	containsNullCaseLabelElement(DetailAST detailAst)	Checks if a switch block contains a null case label.
private static boolean	containsPatternCaseLabelElement(DetailAST detailAst)	Checks if a switch block contains a case label with a pattern variable definition or record pattern definition.
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	hasNullCaseLabel(DetailAST detailAST)	Checks if the case contains null label.
private static boolean	isSwitchExpression(DetailAST ast)	Checks if this LITERAL_SWITCH token is part of a switch expression.
void	visitToken(DetailAST ast)	Called to process a token.

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

beginTree, clearViolations, destroy, finishTree, getFileContents, getFilePath, 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.AbstractAutomaticBean

configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

MSG_KEY

public static final String MSG_KEY

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

See Also:

• Constant Field Values

SWITCH_STATEMENT_PARENTS

private static final Set<Integer> SWITCH_STATEMENT_PARENTS

Represents the possible parent tokens of a switch statement.

Constructor Details

MissingSwitchDefaultCheck

public MissingSwitchDefaultCheck()

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:

• 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

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

containsDefaultLabel

private static boolean containsDefaultLabel(DetailAST detailAst)

Checks if the case group or its sibling contain the 'default' switch.

Parameters:

detailAst - first case group to check.

Returns:

true if 'default' switch found.

containsPatternCaseLabelElement

private static boolean containsPatternCaseLabelElement(DetailAST detailAst)

Checks if a switch block contains a case label with a pattern variable definition or record pattern definition. In this situation, the compiler enforces the given switch block to cover all possible inputs, and we do not need a default label.

Parameters:

detailAst - first case group to check.

Returns:

true if switch block contains a pattern case label element

containsDefaultCaseLabelElement

private static boolean containsDefaultCaseLabelElement(DetailAST detailAst)

Checks if a switch block contains a default case label.

Parameters:

detailAst - first case group to check.

Returns:

true if switch block contains default case label

containsNullCaseLabelElement

private static boolean containsNullCaseLabelElement(DetailAST detailAst)

Checks if a switch block contains a null case label.

Parameters:

detailAst - first case group to check.

Returns:

true if switch block contains null case label

isSwitchExpression

private static boolean isSwitchExpression(DetailAST ast)

Checks if this LITERAL_SWITCH token is part of a switch expression.

Parameters:

ast - the switch statement we are checking

Returns:

true if part of a switch expression

hasNullCaseLabel

private static boolean hasNullCaseLabel(DetailAST detailAST)

Checks if the case contains null label.

Parameters:

detailAST - the switch statement we are checking

Returns:

returnValue the ast of null label