public class MagicNumberCheck extends AbstractCheck
Checks that there are no "magic numbers" where a magic number is a numeric literal that is not defined as a constant. By default, -1, 0, 1, and 2 are not considered to be magic numbers.
Constant definition is any variable/field that has 'final' modifier. It is fine to have one constant defining multiple numeric literals within one expression:
static final int SECONDS_PER_DAY = 24 * 60 * 60;
static final double SPECIAL_RATIO = 4.0 / 3.0;
static final double SPECIAL_SUM = 1 + Math.E;
static final double SPECIAL_DIFFERENCE = 4 - Math.PI;
static final Border STANDARD_BORDER = BorderFactory.createEmptyBorder(3, 3, 3, 3);
static final Integer ANSWER_TO_THE_ULTIMATE_QUESTION_OF_LIFE = new Integer(42);
Check have following options: ignoreHashCodeMethod - ignore magic numbers in hashCode methods; ignoreAnnotation - ignore magic numbers in annotation declarations; ignoreFieldDeclaration - ignore magic numbers in field declarations.
To configure the check with default configuration:
<module name="MagicNumber"/>
results is following violations:
{@literal @}MyAnnotation(6) // violation
class MyClass {
private field = 7; // violation
void foo() {
int i = i + 1; // no violation
int j = j + 8; // violation
}
}
To configure the check so that it checks floating-point numbers that are not 0, 0.5, or 1:
<module name="MagicNumber">
<property name="tokens" value="NUM_DOUBLE, NUM_FLOAT"/>
<property name="ignoreNumbers" value="0, 0.5, 1"/>
<property name="ignoreFieldDeclaration" value="true"/>
<property name="ignoreAnnotation" value="true"/>
</module>
results is following violations:
{@literal @}MyAnnotation(6) // no violation
class MyClass {
private field = 7; // no violation
void foo() {
int i = i + 1; // no violation
int j = j + (int)0.5; // no violation
}
}
Config example of constantWaiverParentToken option:
<module name="MagicNumber">
<property name="constantWaiverParentToken" value="ASSIGN,ARRAY_INIT,EXPR,
UNARY_PLUS, UNARY_MINUS, TYPECAST, ELIST, DIV, PLUS "/>
</module>
result is following violation:
class TestMethodCall {
public void method2() {
final TestMethodCall dummyObject = new TestMethodCall(62); //violation
final int a = 3; // ok as waiver is ASSIGN
final int [] b = {4, 5} // ok as waiver is ARRAY_INIT
final int c = -3; // ok as waiver is UNARY_MINUS
final int d = +4; // ok as waiver is UNARY_PLUS
final int e = method(1, 2) // ELIST is there but violation due to METHOD_CALL
final int x = 3 * 4; // violation
final int y = 3 / 4; // ok as waiver is DIV
final int z = 3 + 4; // ok as waiver is PLUS
final int w = 3 - 4; // violation
final int x = (int)(3.4); //ok as waiver is TYPECAST
}
}
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 |
|---|
MagicNumberCheck()
Constructor for MagicNumber 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 |
setConstantWaiverParentToken(String... tokens)
Sets the tokens which are allowed between Magic Number and defined Object.
|
void |
setIgnoreAnnotation(boolean ignoreAnnotation)
Set whether to ignore Annotations.
|
void |
setIgnoreFieldDeclaration(boolean ignoreFieldDeclaration)
Set whether to ignore magic numbers in field declaration.
|
void |
setIgnoreHashCodeMethod(boolean ignoreHashCodeMethod)
Set whether to ignore hashCode methods.
|
void |
setIgnoreNumbers(double... list)
Sets the numbers to ignore in the check.
|
void |
visitToken(DetailAST ast)
Called to process a token.
|
beginTree, clearMessages, destroy, finishTree, getClassLoader, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, init, isCommentNodesRequired, leaveToken, log, log, log, setClassLoader, setFileContents, setTabWidth, setTokensfinishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverityconfigure, contextualize, getConfiguration, setupChildpublic static final String MSG_KEY
public MagicNumberCheck()
public int[] getDefaultTokens()
AbstractCheckgetDefaultTokens in class AbstractCheckTokenTypespublic int[] getAcceptableTokens()
AbstractCheckgetAcceptableTokens in class AbstractCheckTokenTypespublic int[] getRequiredTokens()
AbstractCheckgetRequiredTokens in class AbstractCheckTokenTypespublic void visitToken(DetailAST ast)
AbstractCheckvisitToken in class AbstractCheckast - the token to processpublic void setConstantWaiverParentToken(String... tokens)
tokens - The string representation of the tokens interested inpublic void setIgnoreNumbers(double... list)
list - list of numbers to ignore.public void setIgnoreHashCodeMethod(boolean ignoreHashCodeMethod)
ignoreHashCodeMethod - decide whether to ignore
hash code methodspublic void setIgnoreAnnotation(boolean ignoreAnnotation)
ignoreAnnotation - decide whether to ignore annotationspublic void setIgnoreFieldDeclaration(boolean ignoreFieldDeclaration)
ignoreFieldDeclaration - decide whether to ignore magic numbers
in field declarationCopyright © 2001–2018. All rights reserved.