Since CodeNarc 1.4
Enforces classes are annotated either with one of the @CompileStatic, @GrailsCompileStatic or @CompileDynamic annotations.
ConfusingTernary RuleSince CodeNarc 0.12
In a ternary expression avoid negation in the test. For example, rephrase: (x != y) ? diff : same as: (x == y) ? same : diff. Consistent use of this rule makes the code easier to read. Also, this resolves trivial ordering problems, such as “does the error case go first?” or “does the common case go first?”.
Example:
(x != y) ? diff : same // triggers violation
(!x) ? diff : same // triggers violation
(x == y) ? same : diff // OK
(x) ? same : diff // OK
// this is OK, because of GroovyTruth there is no inverse of != null
(x != null) ? diff : same
// this is OK, because of GroovyTruth there is no inverse of != true
(x != true) ? diff : same
// this is OK, because of GroovyTruth there is no inverse of != false
(x != false) ? diff : same
Since CodeNarc 0.15
Catch an if block that could be written as an elvis expression.
Example of violations:
if (!x) { // violation
x = 'some value'
}
if (!x) // violation
x = "some value"
if (!params.max) { // violation
params.max = 10
}
x ?: 'some value' // OK
Since CodeNarc 1.0
Checks for three of more if statements that could be converted to a switch. Only applies to equality and instanceof.
Example of violations:
if (x == 1) { // violation
y = x
} else if (x == 2) {
y = x * 2
} else if (x == 3) {
y = x * 3
} else {
y = 0
}
if (y instanceof Integer) { // violation
x = y + 1
}
if (y instanceof String) {
x = y + '1'
} else if (y instanceof Boolean) {
x = !y
} else {
x = null
}
if (x == 1) { // OK
y = x
}
if (x == 2) {
y = x * 2
} else {
y = 0
}
if (!x && y) { // OK
doSomething()
} else if (!x && z) {
doSomethingElse()
} else if (!x && i) {
doAnotherThing()
}
Since CodeNarc 1.1
Checks that field types are explicitly specified (and not using def).
null
Example of violations:
class MyClass {
public static final NAME = "joe" // violation
private static count = 0 // violation
private def name = NAME // violation
protected final date = new Date() // violation
def defaultName // violation
def maxSoFar = -1L // violation
}
Since CodeNarc 0.17
Checks for references to the (effectively) obsolete java.util.Hashtable class. Use the Java Collections Framework classes instead, including HashMap or ConcurrentHashMap. See the JDK javadoc.
Example of violations:
def myMap = new Hashtable() // violation
Since CodeNarc 0.18
Checks for:
An if statement where both the if and else blocks contain only a single return statement returning a constant or literal value.
A block where the second-to-last statement in a block is an if statement with no else, where the block contains a single return statement, and the last statement in the block is a return statement, and both return statements return a constant or literal value. This check is disabled by setting checkLastStatementImplicitElse to false.
Example of violations:
if (condition) { return 44 } else { return 'yes' } // violation
if (check()) { return [1, 2] } else { return "count=$count" } // violation
if (condition) // violation
return null
else return [a:1]
def method1() {
if (condition) { // violation
return 44
}
return 'yes'
}
Since CodeNarc 1.5
Checks for the implicit it closure parameter being used. Also checks if an explicit it parameter has been specified.
it is used, set this property to true. false
Example of violations:
def closureWithViolation = { it * 10 }
def closureWithViolationBecauseOfExplicitItParameter = { it -> it * 10}
<Since CodeNarc 1.6>
Checks for methods that are missing an explicit return statement.
This rule skips void methods and def (dynamic return type) methods, as well as methods whose last statement is a:
throwifforwhiledo .. whileswitchtry/catchExample of violations:
boolean example() { true } // violation
protected int longerExample() {
if (baseName == null) {
return 0
}
99 // violation
}
Note: This rule is pretty much the opposite of the UnnecessaryReturnKeyword rule. Enabling both rules results in a paradox and may cause a rip in the fabric of space-time. Or at least unwanted violations.
InvertedCondition RuleSince CodeNarc 1.1
An inverted condition is one where a constant expression is used on the left hand side of the equals comparision. Such conditions can be confusing especially when used in assertions where the expected value is by convention placed on the right hand side of the comparision.
Example of violations:
boolean isTenCharactersLong(String value) {
10 == value.size() // violation
}
Since CodeNarc 0.11
An inverted if-else statement is one in which there is a single if statement with a single else branch and the boolean test of the if is negated. For instance if (!x) false else true. It is usually clearer to write this as if (x) true else false.
Since CodeNarc 0.16
In Java and Groovy, you can specify long literals with the L or l character, for instance 55L or 24l. It is best practice to always use an uppercase L and never a lowercase l. This is because 11l rendered in some fonts may look like 111 instead of 11L.
Example of violations:
MethodParameterTypeRequired RuleSince CodeNarc 1.1
Checks that method parameters are not dynamically typed, that is they are explicitly stated and different than def.
Property Description Default Value ignoreMethodNames Specifies one or more (comma-separated) method names that should be ignored (i.e., that should not cause a rule violation). The names may optionally contain wildcards (*,?).null
Example of violations:
void methodWithDynamicParameter(def parameter) { // violation
}
void methodWithParameterWithoutTypeDeclaration(parameter) { // violation
}
void methodWithObjectParameter(Object parameter) // OK
Since CodeNarc 1.1
Checks that method return types are not dynamic, that is they are explicitly stated and different than def.
Property Description Default Value ignoreMethodNames Specifies one or more (comma-separated) method names that should be ignored (i.e., that should not cause a rule violation). The names may optionally contain wildcards (*,?).null
Example of violations:
def methodWithDynamicReturnType() { // violation
}
private methodWithoutReturnType() { // violation
}
Object objectReturningMethod() { // OK
}
Since CodeNarc 0.22
Do not allow using the def keyword in code. Use a specific type instead.
def keyword. ’’ NoDouble Rule
Since CodeNarc 1.5
Checks for use of the double or java.lang.Double types, in fields, variables, method parameters, constructor parameters and method return types. Prefer using BigDecimal or int or long, when exact calculations are required. This is due to the limitations and gotchas of the floating point representation of the double type. This is especially important for monetary calculations.
Some related discussions include:
Example of violations:
class MyClass {
int count
double doubleProperty // Violation: Property (field) type
private Double doubleField = 1.2 // Violation: Field type
private double calculateAverage() { return 0 } // Violation: Method return type
protected void setAverage(Double average) { } // Violation: Method parameter type
MyClass(int count, double rating, double factor) { // Violation: Constructor parameter
String name = 'abc'
Double doubleVar = calculateAverage() // Violation: Variable
double double1, double2 = 0 // Violation: Variable
}
}
Since CodeNarc 1.5
Checks for use of the float or java.lang.Float types, in fields, variables, method parameters, constructor parameters and method return types. Prefer using BigDecimal or int or long, when exact calculations are required. This is due to the limitations and gotchas of the floating point representation of the float type. This is especially important for monetary calculations.
Some related discussions include:
Example of violations:
class MyClass {
int count
float floatProperty // Violation: Property (field) type
private Float floatField = 1.2 // Violation: Field type
private float calculateAverage() { return 0 } // Violation: Method return type
protected void setAverage(Float average) { } // Violation: Method parameter type
MyClass(int count, float rating, float factor) { // Violation: Constructor parameter
String name = 'abc'
Float floatVar = calculateAverage() // Violation: Variable
float float1, float2 = 0 // Violation: Variable
}
}
Since CodeNarc 1.2
Do not use the java.util.Date class. Prefer the classes in the java.time.* packages. This rule checks for construction of new java.util.Date objects.
If the class imports another Date class, then references to new Date() will not cause a violation.
Example of violations:
def timestamp = new Date() // violation
Date myDate = new java.util.Date() // violation
Date startTime = new Date(123456789L) // violation
Known limitations:
Date class from the current package. In that case, it may be better to just disable this rule (either per class or globally).Since CodeNarc 0.25
Checks that all source files do not contain the tab character.
NOTE: This is a file-based rule, rather than an AST-based rule, so the applyToClassNames and doNotApplyToClassNames rule configuration properties are not available. See Standard Properties for Configuring Rules. The @SuppressWarnings annotation-based disablement is also unavailable, but including a // codenarc-disable NoTabCharacter comment somewhere above the violation will disable this rule. See Disabling Rules From Comments.
Since CodeNarc 0.17
Checks for a method or closure parameter being reassigned to a new value within the body of the method/closure, which is a confusing and questionable practice. Use a temporary variable instead.
Example of violations:
void myMethod(int a, String b) {
println a
b = 'new value' // violation
}
def myClosure1 = { int a, b ->
a = 123 // violation
}
Since CodeNarc 1.2
Enforce that all public methods are above protected and private methods.
Property Description Default Value ignoreMethodNames Specifies one or more (comma-separated) method names that should be ignored. The named methods will not cause a rule violation, and will not contribute to causing a violation on another method. The names may optionally contain wildcards (*,?).null
Example of violations:
class MyClass {
public static int staticMethod1() { }
protected String method1() { }
static final String staticMethod2() { } // violation
public String method2() { } // violation
private int method3(int id) { }
}
Since CodeNarc 1.2
Enforce that all static fields are above all instance fields within a class
Example of violations:
class MyClass {
public static final int COUNT = 99
public String f1
public static final String F1 = "xxx" // violation
private static String F4 // violation
static F5 = new Date() // violation
protected String f2
}
Since CodeNarc 1.2
Enforce that all static methods within each visibility level (public, protected, private) are above all instance methods within that same visibility level. In other words, public static methods must be above public instance methods, protected static methods must be above protected instance methods and private static methods must be above private instance methods.
Property Description Default Value ignoreMethodNames Specifies one or more (comma-separated) method names that should be ignored. The named methods will not cause a rule violation, and will not contribute to causing a violation on another method. The names may optionally contain wildcards (*,?).null
Example of violations:
class MyClass {
// Public
public static int staticMethod1() { }
public String method1() { }
int method2() { }
static final String staticMethod2(int id) { } // violation
// Protected
protected String method3() { }
protected static staticMethod3() { } // violation
// Private
private int method4() { }
private int method5() { }
private static staticMethod4() { } // violation
private String method5() { }
}
}
Since CodeNarc 0.17
Checks for ternary expressions where the boolean and true expressions are the same. These can be simplified to an Elvis expression.
Example of violations:
x ? x : false // violation; can simplify to x ?: false
foo() ? foo() : bar() // violation; can simplify to foo() ?: bar()
foo(1) ? foo(1) : 123 // violation; can simplify to foo(1) ?: 123
(x == y) ? same : diff // OK
x ? y : z // OK
x ? x + 1 : x + 2 // OK
x ? 1 : 0 // OK
x ? !x : x // OK
!x ? x : null // OK
foo() ? bar() : 123 // OK
foo() ? foo(99) : 123 // OK
foo(x) ? foo() : 123 // OK
foo(1) ? foo(2) : 123 // OK
NOTE: If the boolean and true expressions are the same method call, and that method call has side-effects, then converting it to a Elvis expression may produce different behavior. The method will only be called once, rather than twice. But relying on those side-effects as part of a ternary expression behavior is confusing, error-prone and just a bad idea. In any case, that code should be refactored to move the reliance on the side-effects out of the ternary expression.
TrailingComma RuleSince CodeNarc 0.25
Check whether list and map literals contain an optional trailing comma. Rationale: Putting this comma in makes it easier to change the order of the elements or add new elements on the end.
Property Description Default Value checkList To disable checking List literals, set this property tofalse true checkMap To disable checking Map literals, set this property to false true ignoreSingleElementList If true, skip checking Lists that have only a single element. true ignoreSingleElementMap If true, skip checking Maps that have only a single element. true
This is valid code:
int[] array1 = [] // one line declaration
int[] array2 = [ // empty list
]
int[] array3 = [1,2,3] // one line declaration
int[] array4 = [1,
2,
3, // contains trailing comma
]
int[] array5 = [1,
2] // last element followed by closing bracket on the same line
// NOTE: This style actually violates the intention of this rule
Example of violations:
int[] array2 = [1,
2 // there is no trailing comma
]
Since CodeNarc 1.1
Checks that variable types are explicitly specified in declarations (and not using def).
null
Example of violations:
class MyClass {
void doStuff() {
final NAME = "joe" // violation
def count = 0, max = 99 // violation
def defaultName // violation
}
}
Since CodeNarc 0.17
Checks for references to the (effectively) obsolete java.util.Vector class. Use the Java Collections Framework classes instead, including ArrayList or Collections.synchronizedList(). See the JDK javadoc.
Example of violations:
def myList = new Vector() // violation
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