public final class ThrowsCountCheck extends AbstractCheck
Restricts throws statements to a specified count. Methods with "Override" or "java.lang.Override" annotation are skipped from validation as current class cannot change signature of these methods.
Rationale:
Exceptions form part of a method's interface. Declaring
a method to throw too many differently rooted
exceptions makes exception handling onerous and leads
to poor programming practices such as writing code like
catch(Exception ex). 4 is the empirical value which is based
on reports that we had for the ThrowsCountCheck over big projects
such as OpenJDK. This check also forces developers to put exceptions
into a hierarchy such that in the simplest
case, only one type of exception need be checked for by
a caller but any subclasses can be caught
specifically if necessary. For more information on rules
for the exceptions and their issues, see Effective Java:
Programming Language Guide Second Edition
by Joshua Bloch pages 264-273.
ignorePrivateMethods - allows to skip private methods as they do not cause problems for other classes.
max - Specify maximum allowed number of throws statements.
Type is int.
Default value is 4.
ignorePrivateMethods - Allow private methods to be ignored.
Type is boolean.
Default value is true.
To configure check:
<module name="ThrowsCount"/>
Example:
class Test {
public void myFunction() throws CloneNotSupportedException,
ArrayIndexOutOfBoundsException,
StringIndexOutOfBoundsException,
IllegalStateException,
NullPointerException { // violation, max allowed is 4
// body
}
public void myFunc() throws ArithmeticException,
NumberFormatException { // ok
// body
}
private void privateFunc() throws CloneNotSupportedException,
ClassNotFoundException,
IllegalAccessException,
ArithmeticException,
ClassCastException { // ok, private methods are ignored
// body
}
}
To configure the check so that it doesn't allow more than two throws per method:
<module name="ThrowsCount"> <property name="max" value="2"/> </module>
Example:
class Test {
public void myFunction() throws IllegalStateException,
ArrayIndexOutOfBoundsException,
NullPointerException { // violation, max allowed is 2
// body
}
public void myFunc() throws ArithmeticException,
NumberFormatException { // ok
// body
}
private void privateFunc() throws CloneNotSupportedException,
ClassNotFoundException,
IllegalAccessException,
ArithmeticException,
ClassCastException { // ok, private methods are ignored
// body
}
}
To configure the check so that it doesn't skip private methods:
<module name="ThrowsCount"> <property name="ignorePrivateMethods" value="false"/> </module>
Example:
class Test {
public void myFunction() throws CloneNotSupportedException,
ArrayIndexOutOfBoundsException,
StringIndexOutOfBoundsException,
IllegalStateException,
NullPointerException { // violation, max allowed is 4
// body
}
public void myFunc() throws ArithmeticException,
NumberFormatException { // ok
// body
}
private void privateFunc() throws CloneNotSupportedException,
ClassNotFoundException,
IllegalAccessException,
ArithmeticException,
ClassCastException { // violation, max allowed is 4
// body
}
private void func() throws IllegalStateException,
NullPointerException { // ok
// body
}
}
Parent is com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
throws.count
AutomaticBean.OutputStreamOptions| Modifier and Type | Field and Description |
|---|---|
static String |
MSG_KEY
A key is pointing to the warning message text in "messages.properties"
file.
|
| Constructor and Description |
|---|
ThrowsCountCheck()
Creates new instance of the check.
|
| Modifier and Type | Method and Description |
|---|---|
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 |
setIgnorePrivateMethods(boolean ignorePrivateMethods)
Setter to allow private methods to be ignored.
|
void |
setMax(int max)
Setter to specify maximum allowed number of throws statements.
|
void |
visitToken(DetailAST ast)
Called to process a token.
|
beginTree, clearMessages, destroy, finishTree, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, init, isCommentNodesRequired, leaveToken, log, log, log, setFileContents, setTabWidth, setTokensfinishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverityconfigure, contextualize, getConfiguration, setupChildpublic static final String MSG_KEY
public ThrowsCountCheck()
public int[] getDefaultTokens()
AbstractCheckgetDefaultTokens in class AbstractCheckTokenTypespublic int[] getRequiredTokens()
AbstractCheckgetRequiredTokens in class AbstractCheckTokenTypespublic int[] getAcceptableTokens()
AbstractCheckgetAcceptableTokens in class AbstractCheckTokenTypespublic void setIgnorePrivateMethods(boolean ignorePrivateMethods)
ignorePrivateMethods - whether private methods must be ignored.public void setMax(int max)
max - maximum allowed throws statements.public void visitToken(DetailAST ast)
AbstractCheckvisitToken in class AbstractCheckast - the token to processCopyright © 2001–2020. All rights reserved.