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<h2>Basic Rules ("<i>rulesets/basic.xml</i>")<a name="Basic_Rules_rulesetsbasic.xml"></a></h2><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<div class="section">
<h3>AssertWithinFinallyBlock<a name="AssertWithinFinallyBlock"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for <i>assert</i> statements within a <i>finally</i> block. An <i>assert</i> can throw an exception, hiding the original exception, if there is one.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> int myMethod(int count) {
try {
doSomething()
} finally {
assert count > 0 // violation
}
}
</pre></div></div>
<div class="section">
<h3><a name="AssignmentInConditional">AssignmentInConditional</a> Rule<a name="AssignmentInConditional_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.13</i></p>
<p>An assignment operator (=) was used in a conditional test. This is usually a typo, and the comparison operator (==) was intended.</p>
<p>Example of violations:</p>
<div>
<pre> if ((value = true)) {
// should be ==
}
while (value = true) {
// should be ==
}
(value = true) ? x : y
(value = true) ?: x
// the following code has no violations
if (value == true) {
}
value == true ? x : y
value == true ?: x
</pre></div></div>
<div class="section">
<h3><a name="BigDecimalInstantiation">BigDecimalInstantiation</a> Rule<a name="BigDecimalInstantiation_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for calls to the <tt>java.math.BigDecimal</tt> constructors that take a <tt>double</tt> value as the first parameter. As described in the <tt>BigDecimal</tt> javadoc, the results from these constructors can be somewhat unpredictable, and their use is generally not recommended. This is because some numbers, such as 0.1, cannot be represented exactly as a <tt>double</tt>.</p>
<p>For instance, executing <tt>println new BigDecimal(0.1)</tt> prints out <tt>0.1000000000000000055511151231257827021181583404541015625</tt>.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> def b1 = new BigDecimal(0.1) // violation
def b2 = new java.math.BigDecimal(23.45d) // violation
</pre></div></div>
<div class="section">
<h3><a name="BitwiseOperatorInConditional">BitwiseOperatorInConditional</a> Rule<a name="BitwiseOperatorInConditional_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.15</i></p>
<p>Checks for bitwise operations in conditionals. For instance, the condition <tt>if (a | b)</tt> is almost always a mistake and should be <tt>if (a || b)</tt>. If you need to do a bitwise operation then it is best practice to extract a temp variable.</p>
<p>Example of violations:</p>
<div>
<pre> if (a | b) { }
if (a & b) { }
</pre></div></div>
<div class="section">
<h3><a name="BooleanGetBoolean">BooleanGetBoolean</a> Rule<a name="BooleanGetBoolean_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.13</i></p>
<p>This rule catches usages of java.lang.Boolean.getBoolean(String) which reads a boolean from the System properties. It is often mistakenly used to attempt to read user input or parse a String into a boolean. It is a poor piece of API to use; replace it with System.properties['prop̈́'].</p>
<p>Example of violations:</p>
<div>
<pre> // produces violation
Boolean.getBoolean(value)
// zero or two parameters is OK, must be different method
Boolean.getBoolean(value, 1)
Boolean.getBoolean()
</pre></div></div>
<div class="section">
<h3><a name="BrokenNullCheck">BrokenNullCheck</a> Rule<a name="BrokenNullCheck_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.17</i></p>
<p>Looks for faulty checks for <i>null</i> that can cause a <tt>NullPointerException</tt>.</p>
<p>Examples:</p>
<div>
<pre> if (name != null || name.length > 0) { } // violation
if (name != null || name.length) { } // violation
while (record == null && record.id < 10) { } // violation
if (record == null && record.id && doStuff()) { } // violation
def isNotValid = record == null && record.id < 10 // violation
return record == null && !record.id // violation
if (name != null || name.size() > 0) { } // violation
if (string == null && string.equals("")) { } // violation
def isValid = name != null || name.size() > 0 // violation
return name != null || !name.size() // violation
</pre></div></div>
<div class="section">
<h3><a name="BrokenOddnessCheck">BrokenOddnessCheck</a> Rule<a name="BrokenOddnessCheck_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.13</i></p>
<p>The code uses <tt>x % 2 == 1</tt> to check to see if a value is odd, but this won't work for negative numbers (e.g., <tt>(-5) % 2 == -1)</tt>. If this code is intending to check for oddness, consider using <tt>x & 1 == 1</tt>, or <tt> x % 2 != 0</tt>.</p>
<p>Examples:</p>
<div>
<pre> if (x % 2 == 1) { } // violation
if (method() % 2 == 1) { } // violation
if (x & 1 == 1) { } // OK
if (x % 2 != 0) { } // OK
</pre></div></div>
<div class="section">
<h3><a name="ClassForName">ClassForName</a> Rule<a name="ClassForName_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.14</i></p>
<p>Using <tt>Class.forName(...)</tt> is a common way to add dynamic behavior to a system. However, using this method can cause resource leaks because the classes can be pinned in memory for long periods of time. If you're forced to do dynamic class loading then use ClassLoader.loadClass instead. All variations of the <tt>Class.forName(...)</tt> method suffer from the same problem.</p>
<p>For more information see these links:</p>
<ul>
<li><a class="externalLink" href="http://blog.bjhargrave.com/2007/09/classforname-caches-defined-class-in.html">http://blog.bjhargrave.com/2007/09/classforname-caches-defined-class-in.html</a></li>
<li><a class="externalLink" href="http://www.osgi.org/blog/2011/05/what-you-should-know-about-class.html">http://www.osgi.org/blog/2011/05/what-you-should-know-about-class.html</a></li></ul>
<p>Example of violations:</p>
<div>
<pre> Class.forName('SomeClassName')
Class.forName(aClassName, true, aClassLoader)
</pre></div></div>
<div class="section">
<h3><a name="ComparisonOfTwoConstants">ComparisonOfTwoConstants</a> Rule<a name="ComparisonOfTwoConstants_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.14</i></p>
<p>Checks for expressions where a <i>comparison operator</i> or <tt>equals()</tt> or <tt>compareTo()</tt> is used to compare two constants to each other or two literals that contain only constant values.</p>
<p>Here are examples of code that produces a violation:</p>
<div>
<pre> 23 == 67 // violation
Boolean.FALSE != false // violation
23 < 88 // violation
0.17 <= 0.99 // violation
"abc" > "ddd" // violation
[Boolean.FALSE] >= [27] // violation
[a:1] <=> [a:2] // violation
[1,2].equals([3,4]) // violation
[a:123, b:true].equals(['a':222, b:Boolean.FALSE]) // violation
[a:123, b:456].compareTo([a:222, b:567] // violation
[a:false, b:true].compareTo(['a':34.5, b:Boolean.TRUE] // violation
</pre></div></div>
<div class="section">
<h3><a name="ComparisonWithSelf">ComparisonWithSelf</a> Rule<a name="ComparisonWithSelf_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.14</i></p>
<p>Checks for expressions where a <i>comparison operator</i> or <tt>equals()</tt> or <tt>compareTo()</tt> is used to compare a variable to itself, e.g.: <tt>x == x, x != x, x <=> x, x < x, x >= x, x.equals(x) or x.compareTo(x)</tt>, where <tt>x</tt> is a variable.</p>
<p>Here are examples of code that produces a violation:</p>
<div>
<pre> if (x == x) { } // violation
if (x != x) { } // violation
while (x < x) { } // violation
if (x <= x) { } // violation
while (x > x) { } // violation
if (x >= x) { } // violation
def c = (x <=> x) { } // violation
println isReady = x.equals(x) // violation
println x.compareTo(x) // violation
</pre></div></div>
<div class="section">
<h3><a name="ConstantAssertExpression">ConstantAssertExpression</a> Rule<a name="ConstantAssertExpression_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for <i>assert</i> statements with a constant value for the <i>assert</i> boolean expression, such as <tt>true</tt>, <tt>false</tt>, <tt>null</tt>, or a literal constant value. These <i>assert</i> statements will always pass or always fail, depending on the constant/literal value. Examples of violations include:</p>
<div>
<pre> assert true
assert false, "assertion message"
assert Boolean.TRUE
assert Boolean.FALSE
assert null
assert 0
assert 99.7
assert ""
assert "abc"
assert [:]
assert [a:123, b:456]
assert [a, b, c]
</pre></div></div>
<div class="section">
<h3><a name="ConstantIfExpression">ConstantIfExpression</a> Rule<a name="ConstantIfExpression_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for <i>if</i> statements with a constant value for the <i>if</i> boolean expression, such as <tt>true</tt>, <tt>false</tt>, <tt>null</tt>, or a literal constant value. These <i>if</i> statements can be simplified or avoided altogether. Examples of violations include:</p>
<div>
<pre> if (true) { .. }
if (false) { .. }
if (Boolean.TRUE) { .. }
if (Boolean.FALSE) { .. }
if (null) { .. }
if (0) { .. }
if (99.7) { .. }
if ("") { .. }
if ("abc") { .. }
if ([:]) { .. }
if ([a:123, b:456]) { .. }
if ([a, b, c]) { .. }
</pre></div></div>
<div class="section">
<h3><a name="ConstantTernaryExpression">ConstantTernaryExpression</a> Rule<a name="ConstantTernaryExpression_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for ternary expressions with a constant value for the boolean expression, such as <tt>true</tt>, <tt>false</tt>, <tt>null</tt>, or a literal constant value. Examples of violations include:</p>
<div>
<pre> true ? x : y
false ? x : y
Boolean.TRUE ? x : y
Boolean.FALSE ? x : y
null ? x : y
0 ? x : y
99.7 ? x : y
"" ? x : y
"abc" ? x : y
[:] ? x : y
[a:123, b:456] ? x : y
[a, b, c] ? x : y
</pre></div>
<p>The rule also checks for the same types of constant values for the boolean expressions within the "short" ternary expressions, also known as the "Elvis" operator, e.g.:</p>
<div>
<pre> true ?: y
null ?: y
99.7 ?: y
"abc" ?: y
[:] ?: y
[a, b, c] ?: y
</pre></div></div>
<div class="section">
<h3><a name="DeadCode">DeadCode</a> Rule<a name="DeadCode_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.11</i></p>
<p>Dead code appears after a <tt>return</tt> statement or an exception is thrown. If code appears after one of these statements then it will never be executed and can be safely deleted.</p></div>
<div class="section">
<h3><a name="DoubleNegative">DoubleNegative</a> Rule<a name="DoubleNegative_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.11</i></p>
<p>There is no point in using a double negative, it is always positive. For instance <tt>!!x</tt> can always be simplified to <tt>x</tt>. And <tt>!(!x)</tt> can as well.</p></div>
<div class="section">
<h3><a name="DuplicateCaseStatement">DuplicateCaseStatement</a> Rule<a name="DuplicateCaseStatement_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.11</i></p>
<p>Check for duplicate <tt>case</tt> statements in a <tt>switch</tt> block, such as two equal integers or strings. Here are some examples of code that produces violations:</p>
<div>
<pre> switch( 0 ) {
case 1: break;
case 2: break;
case 2: break; // violation
}
switch( "test" ) {
case "$a": break;
case "$a": break; // ok; only flags constant values (not GStrings)
case "ab": break;
case "ab": break; // violation
case "abc": break;
}
</pre></div></div>
<div class="section">
<h3><a name="DuplicateMapKey">DuplicateMapKey</a> Rule<a name="DuplicateMapKey_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.14</i></p>
<p>A <i>Map</i> literal is created with duplicated key. The map entry will be overwritten.</p>
<p>Example of violations:</p>
<div>
<pre> def var1 = [a:1, a:2, b:3] //violation
def var2 = [1:1, 1:2, 2:3] //violation
def var3 = ["a":1, "a":2, "b":3] //violation
// these are OK
def var4 = [a:1, b:1, c:1]
def var5 = [1:1, 2:1, 3:1]
def var6 = ["a":1, "b":1, "c":1]
</pre></div></div>
<div class="section">
<h3><a name="DuplicateSetValue">DuplicateSetValue</a> Rule<a name="DuplicateSetValue_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.14</i></p>
<p>A <i>Set</i> literal is created with duplicate constant value. A set cannot contain two elements with the same value.</p>
<p>Example of violations:</p>
<div>
<pre> def a = [1, 2, 2, 4] as Set
def b = [1, 2, 2, 4] as HashSet
def c = [1, 2, 2, 4] as SortedSet
def d = [1, 2, 2, 4] as FooSet
def e = ['1', '2', '2', '4'] as Set
def f = ['1', '2', '2', '4'] as HashSet
def g = ['1', '2', '2', '4'] as SortedSet
def h = ['1', '2', '2', '4'] as FooSet
// these are OK
def a = [1, 2, 3, 4] as Set
def b = ['1', '2', '3', '4'] as Set
def c = [1, '1'] as Set
</pre></div></div>
<div class="section">
<h3><a name="EmptyCatchBlock">EmptyCatchBlock</a> Rule<a name="EmptyCatchBlock_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for empty <i>catch</i> blocks. In most cases, exceptions should not be caught and ignored (swallowed).</p>
<p>The rule has a property named <tt>ignoreRegex</tt> that defaults to the value 'ignore|ignored'. If the name of the exception matches this regex then no violations are produced.</p>
<table border="1" class="bodyTable">
<tr class="a">
<td align="left"><b>Property</b></td>
<td align="left"><b>Description</b></td>
<td align="left"><b>Default Value</b></td></tr>
<tr class="b">
<td align="left">ignoreRegex</td>
<td align="left">Regular expression - exception parameter names matching this regular expression are ignored and no volations are produced.</td>
<td align="left">'ignore</td></tr></table>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> def myMethod() {
try {
doSomething
} catch(MyException e) { //violation
// should do something here
}
}
def myMethod() {
try {
doSomething
} catch(MyException ignored) {
//no violations because the parameter name is ignored
}
}
</pre></div></div>
<div class="section">
<h3><a name="EmptyClass">EmptyClass</a> Rule<a name="EmptyClass_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.19</i></p>
<p>Reports classes without methods, fields or properties. Why would you need a class like this?</p>
<p>This rule ignores interfaces, enums, anonymous inner classes, subclasses (extends), and classes with annotations.</p></div>
<div class="section">
<h3><a name="EmptyElseBlock">EmptyElseBlock</a> Rule<a name="EmptyElseBlock_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for empty <i>else</i> blocks. Empty <i>else</i> blocks are confusing and serve no purpose.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> def myMethod() {
if (x==23) {
println 'ok'
} else {
// empty
}
}
</pre></div></div>
<div class="section">
<h3><a name="EmptyFinallyBlock">EmptyFinallyBlock</a> Rule<a name="EmptyFinallyBlock_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for empty <i>finally</i> blocks. Empty <i>finally</i> blocks are confusing and serve no purpose.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> def myMethod() {
try {
doSomething()
} finally {
// empty
}
}
</pre></div></div>
<div class="section">
<h3><a name="EmptyForStatement">EmptyForStatement</a> Rule<a name="EmptyForStatement_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for empty <i>for</i> blocks. Empty <i>for</i> statements are confusing and serve no purpose.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> def myMethod() {
for (int i=0; i < 23; i++) {
// empty
}
}
</pre></div></div>
<div class="section">
<h3><a name="EmptyIfStatement">EmptyIfStatement</a> Rule<a name="EmptyIfStatement_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for empty <i>if</i> statements. Empty <i>if</i> statements are confusing and serve no purpose.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> def myMethod() {
if (x==23) {
// empty
}
}
</pre></div></div>
<div class="section">
<h3><a name="EmptyInstanceInitializer">EmptyInstanceInitializer</a> Rule<a name="EmptyInstanceInitializer_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.13</i></p>
<p>An empty class instance initializer was found. It is safe to remove it. Example:</p>
<div>
<pre> class MyClass {
{ } // empty instance initializer, not a closure
}
</pre></div></div>
<div class="section">
<h3><a name="EmptyMethod">EmptyMethod</a> Rule<a name="EmptyMethod_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.13</i></p>
<p>A method was found without an implementation. If the method is overriding or implementing a parent method, then mark it with the <tt>@Override</tt> annotation. This rule should not be used with Java 5 code because you cannot put <tt>@Override</tt> on a method implementing an interface. Use with Java 6 and higher.</p>
<p>Example of violations:</p>
<div>
<pre> class MyClass {
// violation, empty method
public void method1() {}
// violation, empty method
def method2() {}
// OK because of @Override
@Override
public void method3() {}
}
abstract class MyBaseClass {
// OK, handled by EmptyMethodInAbstractClass Rule
public void method() {}
}
</pre></div></div>
<div class="section">
<h3><a name="EmptyStaticInitializer">EmptyStaticInitializer</a> Rule<a name="EmptyStaticInitializer_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.13</i></p>
<p>An empty static initializer was found. It is safe to remove it. Example:</p>
<div>
<pre> class MyClass {
static { }
}
</pre></div></div>
<div class="section">
<h3><a name="EmptySwitchStatement">EmptySwitchStatement</a> Rule<a name="EmptySwitchStatement_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for empty <i>switch</i> statements. Empty <i>switch</i> statements are confusing and serve no purpose.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> def myMethod() {
switch(myVariable) {
// empty
}
}
</pre></div></div>
<div class="section">
<h3><a name="EmptySynchronizedStatement">EmptySynchronizedStatement</a> Rule<a name="EmptySynchronizedStatement_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for empty <i>synchronized</i> statements. Empty <i>synchronized</i> statements are confusing and serve no purpose.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> class MyClass {
def myMethod() {
synchronized(lock) {
}
}
}
</pre></div></div>
<div class="section">
<h3><a name="EmptyTryBlock">EmptyTryBlock</a> Rule<a name="EmptyTryBlock_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for empty <i>try</i> blocks. Empty <i>try</i> blocks are confusing and serve no purpose.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> def myMethod() {
try {
// empty
} catch(MyException e) {
e.printStackTrace()
}
}
</pre></div></div>
<div class="section">
<h3><a name="EmptyWhileStatement">EmptyWhileStatement</a> Rule<a name="EmptyWhileStatement_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for empty <i>while</i> statements. Empty <i>while</i> statements are confusing and serve no purpose.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> def myMethod() {
while (!stopped) {
// empty
}
}
</pre></div></div>
<div class="section">
<h3><a name="EqualsAndHashCode">EqualsAndHashCode</a> Rule<a name="EqualsAndHashCode_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks that if either the <tt>boolean equals(Object)</tt> or the <tt>int hashCode()</tt> methods are overridden within a class, then both must be overridden.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> class MyClass {
boolean equals(Object object) {
// do something
}
}
</pre></div>
<p>And so does this:</p>
<div>
<pre> class MyClass {
int hashCode() {
return 0
}
}
</pre></div></div>
<div class="section">
<h3><a name="EqualsOverloaded">EqualsOverloaded</a> Rule<a name="EqualsOverloaded_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.14</i></p>
<p>The class has an <tt>equals</tt> method, but the parameter of the method is not of type <tt>Object</tt>. It is not overriding <tt>equals</tt> but instead overloading it.</p>
<p>Example of violations:</p>
<div>
<pre> class Object1 {
//parameter should be Object not String
boolean equals(String other) { true }
}
class Object2 {
// Overloading equals() with 2 parameters is just mean
boolean equals(Object other, String other2) { true }
}
class Object3 {
// a no-arg equals()? What is this supposed to do?
boolean equals() { true }
}
// all of these are OK and do not cause violations
class Object4 {
boolean equals(Object other) { true }
}
@SuppressWarnings('EqualsOverloaded')
class Object5 {
boolean equals(String other) { true }
}
class Object6 {
boolean equals(java.lang.Object other) { true }
}
class Object7 {
boolean equals(other) { true }
}
</pre></div></div>
<div class="section">
<h3><a name="ExplicitGarbageCollection">ExplicitGarbageCollection</a> Rule<a name="ExplicitGarbageCollection_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.12</i></p>
<p>Calls to <tt>System.gc()</tt>, <tt>Runtime.getRuntime().gc()</tt>, and <tt>System.runFinalization()</tt> are not advised. Code should have the same behavior whether the garbage collection is disabled using the option <tt>-Xdisableexplicitgc</tt> or not. Moreover, "modern" JVMs do a very good job handling garbage collections. If memory usage issues unrelated to memory leaks develop within an application, it should be dealt with JVM options rather than within the code itself.</p></div>
<div class="section">
<h3><a name="ForLoopShouldBeWhileLoop">ForLoopShouldBeWhileLoop</a> Rule<a name="ForLoopShouldBeWhileLoop_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.14</i></p>
<p>A <tt>for</tt> loop without an init and update statement can be simplified to a <tt>while</tt> loop.</p>
<p>Example of violations:</p>
<div>
<pre> int i = 0;
for(; i < 5;) { // Violation
println i++
}
// These are OK
for(i in [1,2]) // OK
println i
for(int i = 0; i<5;) // OK
println i++
int i = 0;
for(; i < 5; i++) // OK
println i
for (Plan p : plans) { // OK
println "Plan=$p"
}
</pre></div></div>
<div class="section">
<h3><a name="HardCodedWindowsFileSeparator">HardCodedWindowsFileSeparator</a> Rule<a name="HardCodedWindowsFileSeparator_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.15</i></p>
<p>This rule finds usages of a Windows file separator within the constructor call of a File object. It is better to use the Unix file separator or use the File.separator constant.</p>
<p>Example of violations:</p>
<div>
<pre> new File('.\\foo\\')
new File('c:\\dir')
new File('../foo\\')
</pre></div></div>
<div class="section">
<h3><a name="HardCodedWindowsRootDirectory">HardCodedWindowsRootDirectory</a> Rule<a name="HardCodedWindowsRootDirectory_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.15</i></p>
<p>This rule find cases where a File object is constructed with a windows-based path. This is not portable across operating systems or different machines, and using the File.listRoots() method is a better alternative.</p>
<p>Example of violations:</p>
<div>
<pre> new File('c:\\')
new File('c:\\dir')
new File('E:\\dir')
</pre></div></div>
<div class="section">
<h3><a name="IntegerGetInteger">IntegerGetInteger</a> Rule<a name="IntegerGetInteger_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.13</i></p>
<p>This rule catches usages of java.lang.Integer.getInteger(String, ...) which reads an Integer from the System properties. It is often mistakenly used to attempt to read user input or parse a String into an Integer. It is a poor piece of API to use; replace it with System.properties['prop'].</p>
<p>Example of violations:</p>
<div>
<pre> // violations
Integer.getInteger(value)
Integer.getInteger(value, radix)
// zero or more than 2 parameters is OK, must be different method
Integer.getInteger()
Integer.getInteger(value, radix, locale)
</pre></div></div>
<div class="section">
<h3><a name="MultipleUnaryOperators">MultipleUnaryOperators</a> Rule<a name="MultipleUnaryOperators_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.21</i></p>
<p>Checks for multiple consecutive unary operators. These are confusing, and are likely typos and bugs.</p>
<p>Example of violations:</p>
<div>
<pre> int z = ~~2 // violation
boolean b = !!true // violation
boolean c = !!!false // 2 violations
int j = -~7 // violation
int k = +~8 // violation
</pre></div></div>
<div class="section">
<h3><a name="RandomDoubleCoercedToZero">RandomDoubleCoercedToZero</a> Rule<a name="RandomDoubleCoercedToZero_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>New in CodeNarc 0.15</i></p>
<p>The Math.random() method returns a double result greater than or equal to 0.0 and less than 1.0. If you coerce this result into an Integer, Long, int, or long then it is coerced to zero. Casting the result to int, or assigning it to an int field is probably a bug.</p>
<p>Example of violations:</p>
<div>
<pre> (int) Math.random()
(Integer) Math.random()
int x = Math.random()
Integer y = Math.random()
int m() { Math.random() }
Integer m() { Math.random() }
(Math.random()) as int
(Math.random()) as Integer
</pre></div></div>
<div class="section">
<h3><a name="RemoveAllOnSelf">RemoveAllOnSelf</a> Rule<a name="RemoveAllOnSelf_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p><i>Since CodeNarc 0.11</i></p>
<p>Don't use <tt>removeAll</tt> to clear a collection. If you want to remove all elements from a collection <tt>c</tt>, use <tt>c.clear</tt>, not <tt>c.removeAll(c)</tt>. Calling <tt>c.removeAll(c)</tt> to clear a collection is less clear, susceptible to errors from typos, less efficient and for some collections, might throw a <tt>ConcurrentModificationException</tt>.</p></div>
<div class="section">
<h3><a name="ReturnFromFinallyBlock">ReturnFromFinallyBlock</a> Rule<a name="ReturnFromFinallyBlock_Rule"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for a return from within a <i>finally</i> block. Returning from a <i>finally</i> block is confusing and can hide the original exception.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> int myMethod() {
try {
doSomething()
return 0
} catch(Exception e) {
return -1
} finally {
return 99 // violation
}
}
</pre></div></div>
<div class="section">
<h3>ThrowExceptionFromFinallyBlock<a name="ThrowExceptionFromFinallyBlock"></a></h3><!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
<p>Checks for throwing an exception from within a <i>finally</i> block. Throwing an exception from a <i>finally</i> block is confusing and can hide the original exception.</p>
<p>Here is an example of code that produces a violation:</p>
<div>
<pre> int myMethod() {
try {
doSomething()
throw new Exception()
} finally {
println 'finally'
throw new Exception() // violation
}
}
</pre></div></div></div>
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