Class FallThroughCheck
- All Implemented Interfaces:
Configurable
,Contextualizable
Checks for fall-through in switch
statements.
Finds locations where a case
contains Java code but lacks a
break
, return
, throw
or continue
statement.
The check honors special comments to suppress the warning.
By default the texts
"fallthru", "fall thru", "fall-thru",
"fallthrough", "fall through", "fall-through"
"fallsthrough", "falls through", "falls-through" (case sensitive).
The comment containing these words must be all on one line,
and must be on the last non-empty line before the case
triggering
the warning or on the same line before the case
(ugly, but possible).
switch (i) { case 0: i++; // fall through case 1: i++; // falls through case 2: case 3: case 4: { i++; } // fallthrough case 5: i++; /* fallthru */case 6: i++; // fall-through case 7: i++; break; }
Note: The check assumes that there is no unreachable code in the case
.
The following fragment of code will NOT trigger the check, because of the comment "fallthru" or any Java code in case 5 are absent.
case 3: x = 2; // fallthru case 4: case 5: // violation case 6: break;
-
Property
checkLastCaseGroup
- Control whether the last case group must be checked. Type isboolean
. Default value isfalse
. -
Property
reliefPattern
- Define the RegExp to match the relief comment that suppresses the warning about a fall through. Type isjava.util.regex.Pattern
. Default value is"falls?[ -]?thr(u|ough)"
.
To configure the check:
<module name="FallThrough"/>
or
<module name="FallThrough"> <property name="reliefPattern" value="continue in next case"/> </module>
Parent is com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
-
fall.through
-
fall.through.last
- Since:
- 3.4
-
Nested Class Summary
Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
AutomaticBean.OutputStreamOptions
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Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint[]
The configurable token set.int[]
Returns the default token a check is interested in.int[]
The tokens that this check must be registered for.void
setCheckLastCaseGroup
(boolean value) Setter to control whether the last case group must be checked.void
setReliefPattern
(Pattern pattern) Setter to define the RegExp to match the relief comment that suppresses the warning about a fall through.void
visitToken
(DetailAST ast) Called to process a token.Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
beginTree, 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
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Field Details
-
MSG_FALL_THROUGH
A key is pointing to the warning message text in "messages.properties" file.- See Also:
-
MSG_FALL_THROUGH_LAST
A key is pointing to the warning message text in "messages.properties" file.- See Also:
-
-
Constructor Details
-
FallThroughCheck
public FallThroughCheck()
-
-
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 classAbstractCheck
- Returns:
- the default tokens
- See Also:
-
getRequiredTokens
public int[] getRequiredTokens()Description copied from class:AbstractCheck
The tokens that this check must be registered for.- Specified by:
getRequiredTokens
in classAbstractCheck
- Returns:
- the token set this must be registered for.
- 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 classAbstractCheck
- Returns:
- the token set this check is designed for.
- See Also:
-
setReliefPattern
Setter to define the RegExp to match the relief comment that suppresses the warning about a fall through.- Parameters:
pattern
- The regular expression pattern.
-
setCheckLastCaseGroup
public void setCheckLastCaseGroup(boolean value) Setter to control whether the last case group must be checked.- Parameters:
value
- new value of the property.
-
visitToken
Description copied from class:AbstractCheck
Called to process a token.- Overrides:
visitToken
in classAbstractCheck
- Parameters:
ast
- the token to process
-