Code Quality in Ruby and Java

Code Quality
What is this s**t?

Steve Hayes - Cogent Consulting Pty Ltd
http://www.cogentconsulting.com.au
steve.hayes@cogentconsulting.com.au

Friday, 28 August 2009 1

In 1990 there were 120 billion lines of code


In 2000 there were 250 billion lines of code


In 2010 there will be 500 billion lines of code


Printed in a font 1mm high
the code listing would stretch
from the Earth to the Moon
and beyond


Code Quality


Code quality is subjective - it requires human
judgment


There have been, and always will be, arguments
about code quality


WTF implies lack of clarity


“Simplicity, clarity, singleness: These are the
attributes that give our lives power and vividness
and joy as they are also the marks of great art.
The seem to be the purpose of God for his
whole creation.”

Richard Holloway


Clear code is easier to understand, easier to
maintain, and easier to extend


There are many things that can reduce the clarity
of code, including:

• inconsistent style
• long methods
• lots of methods in a single class
• repeated code
• methods with many alternative paths


Your particular bugbears may be different


Why metrics?


We substitute metrics for human judgement


People are expensive, CPU time is cheap


Use automation to detect clarity problems, such
as:

• inconsistent style
• long methods
• lots of methods in a single class
• repeated code
• methods with many alternative paths


Use exception based reporting so that people can
focus their energy


on the quality exceptions


or on completely different things


Code Analysis


Let’s start with some Ruby

Formtastic by Justin French


Then we’ll move on to some Java


Duplication


Duplication makes everything else worse


Initial analysis of Formtastic


37 Roodi problems

95 Flog problems


Simian
http://www.redhillconsulting.com.au/products/simian/


Simian - Similarity Analyser | Duplicate Code Detection for the Enterprise 14/08/09 3:41 AM

Simian - Similarity Analyser
Purpose
Simian (Similarity Analyser) identifies duplication in Java, C#, C, C++, COBOL, Ruby, JSP, ASP,
HTML, XML, Visual Basic, Groovy source code and even plain text files. In fact, simian can be used on
any human readable files such as ini files, deployment descriptors, you name it.

Especially on large enterprise projects, it can be difficult for any one developer to keep track of all the
features (classes, methods, etc.) of the system.

Simian runs natively in any .NET 1.1 or higher supported environment and on any Java 1.4 or higher
virtual machine, meaning Simian can be run on just about any hardware and any operating system you
can hope for. Both the Java and .NET runtimes are included as part of the distribution.

Simian can be used as part of the build process during development or as a guide when re-factoring.
Think of Simian as an independent pair of eyes that will assist in raising the quality of your software.

Within minutes, Simian can save you literally thousands of dollars in time spent performing maintenence,
debugging and re-factoring.

With licensing available to suite personal, project and enterprise use, simian is ideally suited for use on
your project.

Why do I need Simian?
Imagine for example that a bug is discovered in a method somewhere in a project. The developer duly
writes a test case, makes the necessary code changes, ensures the test passes, checks the code in and
considers the job finished!

Right?

Simian highlights obvious duplication


Similarity Analyser 2.2.24 - http://www.redhillconsulting.com.au/products/simian/index.html
Copyright (c) 2003-08 RedHill Consulting Pty. Ltd. All rights reserved.
Simian is not free unless used solely for non-commercial or evaluation purposes.
{failOnDuplication=true, ignoreCharacterCase=true, ignoreCurlyBraces=true, ignoreIdentifierCase=true,
ignoreModifiers=true, ignoreStringCase=true, threshold=6}
Found 7 duplicate lines in the following files:
Between lines 949 and 962 in /Users/stevehayes/projects/third-party/formtastic/spec/formtastic_spec.rb
Found 50 duplicate lines in 6 blocks in 1 files
Processed a total of 2066 significant (4341 raw) lines in 6 files
Processing time: 0.144sec


Flay
http://ruby.sadi.st/Flay.html


Confessions of a Ruby Sadist sudo gem install flay 14/08/09 3:46 AM

Ruby Sadist Flog Flay Heckle Kittens About Us

Confessions of a Ruby Sadist
sudo gem install flay

Flay analyzes ruby code for
structural similarities. Differences
in literal values, names,
whitespace, and programming
style are all ignored.

Code that flay reports as similar
is a good candidate for
refactoring.

Try this:

% sudo gem install
flay
% flay lib/*.rb

and see what you find.


Flay detects more subtle duplication


Total score (lower is better) = 2637 8) Similar code found in :iter (mass = 96)
spec/formtastic_spec.rb:1825
1) Similar code found in :iter (mass = 342) spec/formtastic_spec.rb:1844
spec/formtastic_spec.rb:1570 spec/formtastic_spec.rb:1877
2) Similar code found in :iter (mass = 136)
spec/formtastic_spec.rb:1183 9) Similar code found in :iter (mass = 92)
10) Similar code found in :block (mass = 84)
3) IDENTICAL code found in :iter (mass*2 = 136) spec/formtastic_spec.rb:1900
11) IDENTICAL code found in :block (mass*2 = 84)
6) Similar code found in :iter (mass = 100) spec/formtastic_spec.rb:1208

7) Similar code found in :iter (mass = 98) 14) Similar code found in :iter (mass = 75)


So what did I do?


move lines around

change similar code to be the same

changed in-line constants to variables


these are often non-trivial changes


very little change in overall ﬁle length

(3013 => 2897 lines)


How did that change complexity?


37 => 37 Roodi problems

95 => 38 Flog problems


Flog change indicates that methods have
become simpler


Exacerbation


What else exacerbates problems?


Long classes and methods


http://farm4.static.ﬂickr.com/3060/2426522019_7e696fb9af.jpg


Tools that detect long classes and methods are
simple but useful


Roodi
Ruby Object Oriented Design Inferometer
http://github.com/martinjandrews/roodi/tree/master


General Purpose Code Quality


Roodi checks

AssignmentInConditionalCheck Check for an assignment inside a conditional. It‘s probably a mistaken equality comparison.

CaseMissingElseCheck Check that case statements have an else statement so that all cases are covered.

ClassLineCountCheck Check that the number of lines in a class is below the threshold.

ClassNameCheck Check that class names match convention.

CyclomaticComplexityBlockCheck Check that the cyclomatic complexity of all blocks is below the threshold.

CyclomaticComplexityMethodCheck Check that the cyclomatic complexity of all methods is below the threshold.

EmptyRescueBodyCheck Check that there are no empty rescue blocks.

ForLoopCheck Check that for loops aren‘t used (Use Enumerable.each instead)

MethodLineCountCheck Check that the number of lines in a method is below the threshold.

MethodNameCheck Check that method names match convention.

ModuleLineCountCheck Check that the number of lines in a module is below the threshold.

ModuleNameCheck Check that module names match convention.

ParameterNumberCheck Check that the number of parameters on a method is below the threshold.


Roodi parameters

AssignmentInConditionalCheck

CaseMissingElseCheck

ClassLineCountCheck 300

ClassNameCheck pattern: !ruby/regexp /^[A-Z][a-zA-Z0-9]*$/

CyclomaticComplexityBlockCheck 4

CyclomaticComplexityMethodCheck 8

EmptyRescueBodyCheck

ForLoopCheck

MethodLineCountCheck 20

MethodNameCheck pattern: !ruby/regexp /^[_a-z<>=[]|+-/*`]+[_a-z0-9_<>=~@[]]*[=!?]?$/

ModuleLineCountCheck 300

ModuleNameCheck pattern: !ruby/regexp /^[A-Z][a-zA-Z0-9]*$/

ParameterNumberCheck 5


lib/formtastic.rb:8 - Module "Formtastic" has 1272 lines. It should have 300 or less.
lib/formtastic.rb:10 - Class "SemanticFormBuilder" has 1196 lines. It should have 300 or less.
lib/formtastic.rb:742 - Method "date_or_datetime_input" has 33 lines. It should have 20 or less.
lib/formtastic.rb:835 - Method "check_boxes_input" has 24 lines. It should have 20 or less.
lib/formtastic.rb:1008 - Method "default_input_type" has 24 lines. It should have 20 or less.
lib/formtastic.rb:1046 - Method "find_collection_for_column" has 27 lines. It should have 20 or less.
lib/formtastic.rb:1180 - Method "localized_attribute_string" has 24 lines. It should have 20 or less.
lib/formtastic.rb:742 - Method name "date_or_datetime_input" cyclomatic complexity is 10. It should be 8 or less.
lib/formtastic.rb:1008 - Method name "default_input_type" cyclomatic complexity is 19. It should be 8 or less.
lib/formtastic.rb:1046 - Method name "find_collection_for_column" cyclomatic complexity is 10. It should be 8 or less.
lib/formtastic.rb:756 - Block cyclomatic complexity is 5. It should be 4 or less.
lib/formtastic.rb:1027 - Found = in conditional. It should probably be an ==
lib/formtastic.rb:1188 - Rescue block should not be empty.
lib/formtastic.rb:103 - Don't use class variables. You might want to try a different design.


spec/formtastic_spec.rb:38 - Block cyclomatic complexity is 5. It should be 4 or less.
spec/formtastic_spec.rb:109 - Case statement is missing an else clause.


Let’s work through the spec ﬁrst


spec/formtastic_spec.rb:38 - Block cyclomatic
complexity is 5. It should be 4 or less.


spec/formtastic_spec.rb:109 - Case statement
is missing an else clause.


Existing code

Post.stub!(:reflect_on_association).and_return do |column_name|
case column_name
when :author, :author_status
mock('reflection', :options => {},
:klass => Author,
:macro => :belongs_to)
when :authors
:klass => Author,
:macro => :has_and_belongs_to_many)
end
end


New code

def mock_post_association(column_name)
return mock_association(Author, :belongs_to) if column_name.is_post_belongs_to?
return mock_association(Author, :has_and_belongs_to_many) if
column_name.is_post_habtm?
end

def mock_association(klass, multiplicity)
:klass => klass,
:macro => multiplicity)
end
...
Post.stub!(:reflect_on_association).and_return
{ |column_name|mock_post_association(column_name) }


Not worth addressing these


Back to the non-test code


lib/formtastic.rb:742 - Method "date_or_datetime_input" has 33 lines. It should have 20 or less.
lib/formtastic.rb:835 - Method "check_boxes_input" has 24 lines. It should have 20 or less.
lib/formtastic.rb:1008 - Method "default_input_type" has 24 lines. It should have 20 or less.
lib/formtastic.rb:1046 - Method "find_collection_for_column" has 27 lines. It should have 20 or less.
lib/formtastic.rb:1180 - Method "localized_attribute_string" has 24 lines. It should have 20 or less.
lib/formtastic.rb:742 - Method name "date_or_datetime_input" cyclomatic complexity is 10. It should be 8 or less.
lib/formtastic.rb:1008 - Method name "default_input_type" cyclomatic complexity is 19. It should be 8 or less.
lib/formtastic.rb:1046 - Method name "find_collection_for_column" cyclomatic complexity is 10. It should be 8 or less.
lib/formtastic.rb:756 - Block cyclomatic complexity is 5. It should be 4 or less.


(and now I make lots of code changes)


and I decide that’s enough for now


How does this change ﬂog?


Old and new flog warnings

>88.1: SemanticFormBuilder#date_or_datetime_input 60.4: SemanticFormBuilder#inputs
60.4: SemanticFormBuilder#inputs 58.4: SemanticFormBuilder#input
58.4: SemanticFormBuilder#input 45.3: SemanticFormBuilder#database_column_input_type
>57.7: SemanticFormBuilder#find_collection_for_column 43.3: SemanticFormBuilder#field_set_and_list_wrapping
-56.9: SemanticFormBuilder#default_input_type 40.2: SemanticFormBuilder#radio_input
>48.3: SemanticFormBuilder#localized_attribute_string 38.4: SemanticFormBuilder#localized_attribute_string
-44.3: SemanticFormBuilder#check_boxes_input 31.4:
43.3: SemanticFormBuilder#field_set_and_list_wrapping SemanticFormBuilder#find_collection_for_column_explicit_or_asso
40.2: SemanticFormBuilder#radio_input ciation_or_boolean
31.2: SemanticFormBuilder#inputs_for_nested_attributes 31.2: SemanticFormBuilder#inputs_for_nested_attributes
24.0: SemanticFormBuilder#label 29.5: SemanticFormBuilder#datetime_content_tag
22.7: SemanticFormBuilder#method_required? 28.1: SemanticFormBuilder#find_collection_for_column
20.0: SemanticFormBuilder#none 26.0: SemanticFormBuilder#single_list_item_content_from
24.0: SemanticFormBuilder#label
22.7: SemanticFormBuilder#method_required?
20.2: SemanticFormBuilder#date_or_datetime_input
20.0: SemanticFormBuilder#none


Changes

>88.1: SemanticFormBuilder#date_or_datetime_input 45.3: SemanticFormBuilder#database_column_input_type
>57.7: SemanticFormBuilder#find_collection_for_column 38.4: SemanticFormBuilder#localized_attribute_string
-56.9: SemanticFormBuilder#default_input_type 31.4:
>48.3: SemanticFormBuilder#localized_attribute_string SemanticFormBuilder#find_collection_for_column_explicit_
-44.3: SemanticFormBuilder#check_boxes_input or_association_or_boolean
29.5: SemanticFormBuilder#datetime_content_tag
28.1: SemanticFormBuilder#find_collection_for_column
26.0: SemanticFormBuilder#single_list_item_content_from
20.2: SemanticFormBuilder#date_or_datetime_input


So what’s Flog?


Confessions of a Ruby Sadist sudo gem install flog 14/08/09 3:34 AM

Ruby Sadist Flog Flay Heckle Kittens About Us

Confessions of a Ruby Sadist
sudo gem install flog

Flog shows you the most
torturous code you wrote.
The more painful the code,
the higher the score. The
higher the score, the
harder it is to test.

Run it against your best
stuff. I double-dog dare you.
So what’s Flog?
Flog essentially scores an
ABC metric: Assignments,
Branches, Calls, with
particular attention placed
on calls.

Run flog on all your code.
Try this:

find lib -name *.rb | xargs flog

Whatever is at the top of the
report is worth looking at.

This is how it works:


Confessions of a Ruby Sadist sudo gem install flog 14/08/09 3:34 AM

class Test
class Test
def blah # 11.2 =
def blah
a = eval "1+1" # 1.2 + 6.0 +
a = eval "1+1"
if a == 2 then # 1.2 + 1.2 +
if a == 2 then Is seen by
0.4 +
puts "yay" flog as: puts "yay" # 1.2
end
end
end
end
end
end

Test#blah: (11.2)
6.0: eval
1.2: branch
and reported 1.2: ==
as: 1.2: puts
1.2: assignment
0.4: lit_fixnum


Flog weights
THRESHOLD = 0.60
SCORES = Hash.new 1 # various "magic" usually used for "clever code"
BRANCHING = SCORES.merge!(:alias_method => 2,
[ :and, :case, :else, :if, :or, :rescue, :until, :extend => 2,
:when, :while ] :include => 2,
:instance_method => 2,
# various non-call constructs :instance_methods => 2,
OTHER_SCORES = { :method_added => 2,
:alias => 2, :method_defined? => 2,
:assignment => 1, :method_removed => 2,
:block => 1, :method_undefined => 2,
:block_pass => 1, :private_class_method => 2,
:branch => 1, :private_instance_methods => 2,
:lit_fixnum => 0.25, :private_method_defined? => 2,
:sclass => 5, :protected_instance_methods => 2,
:super => 1, :protected_method_defined? => 2,
:to_proc_icky! => 10, :public_class_method => 2,
:to_proc_normal => 5, :public_instance_methods => 2,
:yield => 1, :public_method_defined? => 2,
} :remove_method => 2,
:send => 3,
# eval forms :undef_method => 2)
SCORES.merge!(:define_method => 5,
:eval => 5, # calls I don't like and usually see being
:module_eval => 5, abused
:class_eval => 5,
:instance_eval => 5) SCORES.merge!(:inject => 2)


ﬂog -d lib/formtastic.rb


Flog details for worst method
60.4: SemanticFormBuilder#inputs
16.6: assignment
11.9: branch
11.5: to_proc_normal
5.8: block_pass
5.7: map
4.8: class
3.3: field_set_and_list_wrapping
2.3: content_columns
2.2: macro
2.1: reflections
2.0: ==
2.0: to_sym
1.9: compact!
1.9: +
1.9: -
1.8: empty?
1.8: input
1.5: block_given?
1.5: inputs_for_nested_attributes
1.4: extract_options!
1.4: []


Original code

def inputs(*args, &block)
html_options = args.extract_options!
html_options[:class] ||= "inputs"

if html_options[:for]
inputs_for_nested_attributes(args, html_options, &block)
elsif block_given?
field_set_and_list_wrapping(html_options, &block)
else
if @object && args.empty?
args = @object.class.reflections.map { |n,_| n if _.macro == :belongs_to }
args += @object.class.content_columns.map(&:name)
args -= %w[created_at updated_at created_on updated_on lock_version]
args.compact!
end
contents = args.map { |method| input(method.to_sym) }

field_set_and_list_wrapping(html_options, contents)
end
end


First change

elsif block_given?
else
args = build_default_inputs_args
end
contents = args.map { |method| input(method.to_sym) }
end
end

def build_default_inputs_args()
args.compact!
end


Flog details
29.8: SemanticFormBuilder#build_default_inputs_args
9.0: to_proc_normal
8.7: assignment
3.8: class
3.0: map
2.9: branch
1.8: block_pass
1.7: macro
1.6: reflections
1.5: ==
1.4: compact!
1.4: -
1.4: +

24.1: SemanticFormBuilder#inputs
8.0: branch
6.7: assignment
3.5: block_pass
3.3: field_set_and_list_wrapping
2.0: to_sym
1.8: empty?
1.8: build_default_inputs_args
1.8: input
1.7: map
1.5: inputs_for_nested_attributes
1.5: block_given?
1.4: extract_options!
1.4: []


Next change

elsif block_given?
else
contents = inputs_contents(args)
end
end

def inputs_contents(args)
args = build_default_inputs_args
end
return args.map { |method| input(method.to_sym) }
end

args.compact!
end


Flog details - only one signiﬁcant method

9.0: to_proc_normal
8.7: assignment
3.8: class
3.0: map
2.9: branch
1.8: block_pass
1.7: macro
1.6: reflections
1.5: ==
1.4: compact!
1.4: -
1.4: +


Inline to_proc

args += @object.class.content_columns.map {|c| c.name}
args.compact!
end


Flog details

10.4: assignment
4.5: branch
3.8: class
3.0: map
1.7: name
1.7: macro
1.6: reflections
1.5: ==
1.4: compact!
1.4: -


Extract method

args += content_column_names
args.compact!
end

def content_column_names
return @object.class.content_columns.map {|c| c.name}
end


Flog details

8.7: assignment
2.9: branch
1.8: class
1.7: macro
1.6: content_column_names
1.6: reflections
1.5: ==
1.4: compact!
1.4: map
1.4: -
1.4: +


and so forth...


Other Ruby code quality tools


Code churn metric


Saikuro : A Cyclomatic Complexity Analyzer 14/08/09 5:05 AM

Saikuro
A Cyclomatic Complexity Analyzer
Download Saikuro

Saikuro is a Ruby cyclomatic complexity analyzer. When given
Ruby source code Saikuro will generate a report listing the
cyclomatic complexity of each method found. In addition,
Saikuro counts the number of lines per method and can
generate a listing of the number of tokens on each line of code.

Version:
0.2

License
Saikuro uses the BSD license.

Example Output
Here are examples of the output generated by Saikuro.
Cyclomatic complexity summary page
Token count summary page

Installation
As root run:
# ruby setup.rb all

Usage
Saikuro is a command line program. Running "saikuro.rb -h" will
output a usage statement describing all the various arguments
you can pass to it.
"saikuro -c -p tests/samples.rb"
The above command is a simple example that generates a
cyclomatic complexity report on the samples.rb file, using the
default filter, warning and error settings. The report is saved in
the current directory.
A more detailed example is :
Friday, 28 August 2009 "saikuro -c -t -i tests -y 0 -w 11 -e 16 -o out/" 93

reek, a code smells detector for ruby « silk and spinach 14/08/09 5:06 AM

silk and spinach
development, by example

reek, a code smells detector for ruby
with 23 comments

To complement the imminent (ie. sometime next year) publication of the Ruby Refactoring Workbook
I’ve been working on a little software tool called ‘reek’. Reek scans ruby code — either source files or
in-memory Class objects — looking for some of the code smells discussed in the book. Right now it can
detect (certain forms of):

Long Method
Large Class
Feature Envy
Uncommunicative Name
Long Parameter List
Utility Function
Nested Iterators

As time goes by I’ll be adding checks for more smells, and I hope to make the current checks a bit more
sophisticated. But in the agile spirit of going ugly early, the current very early version is available for
you to experiment with. To get the tool:
gem install reek

To run it:
reek file1.rb file2.rb ...

If you try it, please let me know what you think and what you’d like the next version to do!

You can browse the reek project’s code repository at http://github.com/kevinrutherford/reek/tree/master
or http://rubyforge.org/projects/reek/, both of which are clones of the same Git repository.

RCov - Ruby C0 Code Coverage 15/08/09 12:11 PM

RCov
RCov - Ruby C0 Code Coverage

Source

Install
$ gem install relevance-rcov

Usage
See the README on GitHub for the most-up to date usage of RCov.

Maintained by Relevance


metric fu


rake metrics:all


results at
ﬁle:///Users/stevehayes/projects/third-party/
formtastic/tmp/metric_fu/output/index.html


Java time


Example code is from Apache
Commons Collections 3.2.1


Simian for duplication detection


java -jar simian-2.2.24.jar src/**/*.java


Found 11527 duplicate lines in 871 blocks in 239 files

Processed a total of 41324 significant (109875 raw)
lines in 467 files

Processing time: 2.404sec


27.9% of the code is duplicated


Simian can also be language
sensitive


java -jar simian-2.2.24.jar
-language=java src/**/*.java


PMD for duplication detection


Android Rules: These rules deal with the Android SDK, mostly related to best practices. To get better results, make sure
that the auxclasspath is defined for type resolution to work.
• Basic JSF rules: Rules concerning basic JSF guidelines.
• Basic JSP rules: Rules concerning basic JSP guidelines.
• Basic Rules: The Basic Ruleset contains a collection of good practices which everyone should follow.
• Braces Rules: The Braces Ruleset contains a collection of braces rules.
• Clone Implementation Rules: The Clone Implementation ruleset contains a collection of rules that find questionable usages
of the clone() method.
• Code Size Rules: The Code Size Ruleset contains a collection of rules that find code size related problems.
• Controversial Rules: The Controversial Ruleset contains rules that, for whatever reason, are considered controversial. They
are separated out here to allow people to include as they see fit via custom rulesets. This ruleset was initially created in
response to discussions over UnnecessaryConstructorRule which Tom likes but most people really dislike :-)
• Coupling Rules: These are rules which find instances of high or inappropriate coupling between objects and packages.
• Design Rules: The Design Ruleset contains a collection of rules that find questionable designs.
• Finalizer Rules: These rules deal with different problems that can occur with finalizers.
• Import Statement Rules: These rules deal with different problems that can occur with a class' import statements.
• J2EE Rules: These are rules for J2EE
• JavaBean Rules: The JavaBeans Ruleset catches instances of bean rules not being followed.
• JUnit Rules: These rules deal with different problems that can occur with JUnit tests.
• Jakarta Commons Logging Rules: The Jakarta Commons Logging ruleset contains a collection of rules that find questionable
usages of that framework.
• Java Logging Rules: The Java Logging ruleset contains a collection of rules that find questionable usages of the logger.
• Migration Rules: Contains rules about migrating from one JDK version to another. Don't use these rules directly, rather, use
a wrapper ruleset such as migrating_to_13.xml.
• Migration13: Contains rules for migrating to JDK 1.3
• MigratingToJava4: Contains rules for migrating to JDK 1.5
• Naming Rules: The Naming Ruleset contains a collection of rules about names - too long, too short, and so forth.
• Optimization Rules: These rules deal with different optimizations that generally apply to performance best practices.
• Strict Exception Rules: These rules provide some strict guidelines about throwing and catching exceptions.
• String and StringBuffer Rules: These rules deal with different problems that can occur with manipulation of the class String
or StringBuffer.
• Security Code Guidelines: These rules check the security guidelines from Sun, published at http://java.sun.com/security/
seccodeguide.html#gcg
• Type Resolution Rules: These are rules which resolve java Class files for comparisson, as opposed to a String


Basic Rules: The Basic Ruleset contains a collection of good practices which everyone should follow.
• Braces Rules: The Braces Ruleset contains a collection of braces rules.
• Clone Implementation Rules: The Clone Implementation ruleset contains a collection of rules that find questionable usages
of the clone() method.
• Code Size Rules: The Code Size Ruleset contains a collection of rules that find code size related problems.
• Coupling Rules: These are rules which find instances of high or inappropriate coupling between objects and packages.
• Design Rules: The Design Ruleset contains a collection of rules that find questionable designs.
• Import Statement Rules: These rules deal with different problems that can occur with a class' import statements.
• JUnit Rules: These rules deal with different problems that can occur with JUnit tests.
• Naming Rules: The Naming Ruleset contains a collection of rules about names - too long, too short, and so forth.
• Optimization Rules: These rules deal with different optimizations that generally apply to performance best practices.
• Strict Exception Rules: These rules provide some strict guidelines about throwing and catching exceptions.
• String and StringBuffer Rules: These rules deal with different problems that can occur with manipulation of the class String
or StringBuffer.
• Type Resolution Rules: These are rules which resolve java Class files for comparisson, as opposed to a String
• Unused Code Rules: The Unused Code Ruleset contains a collection of rules that find unused code.


Basic Rules
• Empty catch block • Unnecessary final modifier
• Empty if Statement • Collapsible if statements
• Empty while statement • Useless overriding method
• Empty try block • Class cast exception with toArray
• Empty finally block • Avoid decimal literals in BigDecimal
• Empty switch statements constructor
• Jumbled incrementer • Useless operation on immutable
• For loop should be while loop • Misplaced null check
• Unnecessary conversion temporary • Unused null check in equals
• Override both equals and hashcode • Avoid thread group
• Double checked locking • Broken null check
• Return from finally block • BigInteger instantiation
• Empty synchronized block • Avoid using octal values
• Unnecessary return • Avoid using hardcoded IP
• Empty static initializer • Check result set
• Unconditional if statement • Avoid multiple unary operators
• Empty statement not in loop • Empty initializer
• Boolean instantiation


Basic Rules - 725
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/BeanMap.java:308
Overriding method merely calls super
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/ExtendedProperties.java:410
Avoid empty catch blocks
These nested if statements could be combined
Avoid instantiating Boolean objects; reference
Boolean.TRUE or Boolean.FALSE or call Boolean.valueOf() instead.
Avoid instantiating Boolean objects; reference
Boolean.TRUE or Boolean.FALSE or call Boolean.valueOf() instead.
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/IteratorUtils.java:907
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/LRUMap.java:120
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/MapUtils.java:170
Avoid instantiating Boolean objects; reference Boolean.TRUE or
Boolean.FALSE or call Boolean.valueOf() instead.
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/MultiHashMap.java:138
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/ReferenceMap.java:598
Avoid empty while statements
Ensure you override both equals() and hashCode()
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/StaticBucketMap.java:159
Unnecessary final modifier in final class
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/functors/PrototypeFactory.java:195
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/functors/PrototypeFactory.java:202
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/iterators/FilterIterator.java:108
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/iterators/FilterListIterator.java:140
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/iterators/FilterListIterator.java:156
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/iterators/ObjectGraphIterator.java:141
Avoid empty if statements
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/list/CursorableLinkedList.java:428
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/AbstractReferenceMap.java:278
Avoid empty while statements
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/CaseInsensitiveMap.java:133
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/HashedMap.java:96
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/IdentityMap.java:175
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/LRUMap.java:395
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/LinkedMap.java:117
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/StaticBucketMap.java:160


Braces Rules

• If statements must use braces
• While loops must use braces
• If else statements must use braces
• For loops must use braces


Braces Rules - 210
Avoid using if statements without curly braces
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/BinaryHeap.java:476
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/BoundedFifoBuffer.java:272
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/FastArrayList.java:370
Avoid using if...else statements without curly braces
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/FastHashMap.java:592
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/FastTreeMap.java:700
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/LRUMap.java:92
Avoid using while statements without curly braces
Avoid using while statements without curly braces


Clone Rules

• Proper clone implementation (should include super.clone())
• Clone throws CloneNotSupportedException
• Clone method must implement cloneable


Clone Rules - 25
Object clone() should be implemented with super.clone()
clone() method should be implemented only if implementing
Cloneable interface
clone() method should throw CloneNotSupportedException
Cloneable interface
Cloneable interface
Cloneable interface
clone() method should throw
CloneNotSupportedException
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/AbstractHashedMap.java:1227
clone() method should be implemented only if
implementing Cloneable interface
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/AbstractHashedMap.java:1227
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/CaseInsensitiveMap.java:133
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/Flat3Map.java:1014
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/HashedMap.java:96
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/IdentityMap.java:175
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/LRUMap.java:395
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/LinkedMap.java:117
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/MultiKeyMap.java:818
Cloneable interface
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/SingletonMap.java:538
/Users/stevehayes/commons-collections-3.2.1-src/src/test/org/apache/commons/collections/BulkTest.java:177


Code Size Rules

• NPath complexity (200)
• Excessive method length (100)
• Excessive parameter list (10)
• Excessive class length (1000)
• Cyclomatic complexity (10)
• Excessive public count (45)
• Too many ﬁelds (15)
• NCSS method count (100)
• NCSS type count (1500)
• NCSS constructor count (100)
• Too many methods (10)


Code Size Rules - 338
This class has too many methods, consider refactoring it.
The class 'BinaryHeap' has a Cyclomatic Complexity of 2 (Highest =
14).
The method 'iterator' has a Cyclomatic Complexity of 14.
The method 'remove' has a Cyclomatic Complexity of 10.
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/ClosureUtils.java:57
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/CollectionUtils.java:17
his class has a bunch of public methods and attributes
T
void really long classes.
A
he class 'CollectionUtils' has a Cyclomatic Complexity of 3
T
(Highest = 14).
his class has too many methods, consider refactoring it.
T
The method 'index' has a Cyclomatic Complexity of 13.
The method 'get' has a Cyclomatic Complexity of 14.
The method 'size' has a Cyclomatic Complexity of 10.
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/ComparatorUtils.java:44
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/CursorableLinkedList.java:17
This class has a bunch of public methods and attributes
Avoid really long classes.
T
he method insertListable() has an NPath complexity of
T
200
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/DefaultMapBag.java:48
T
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/DoubleOrderedMap.java:17
This class has a bunch of public methods and attributes
Avoid really long classes.
The class 'DoubleOrderedMap' has a Cyclomatic
Complexity of 4 (Highest = 15).
The method 'entrySetByValue' has a Cyclomatic Complexity
of 12.
The method 'valuesByValue' has a Cyclomatic Complexity
of 11.
The method 'doRedBlackInsert' has a Cyclomatic
Complexity of 11.
The method 'doRedBlackDelete' has a Cyclomatic
Complexity of 13.
The method 'doRedBlackDeleteFixup' has a Cyclomatic
Complexity of 12.
The method 'swapPosition' has a Cyclomatic Complexity of


Coupling Rules

• Coupling between objects (attributes, local variables,
return types) (20)
• Excessive imports (30)
• Loose coupling (avoid using implementation types, use
interface instead)


Coupling Rules - 63
Avoid using implementation types like 'HashMap'; use the interface
instead
instead
instead
instead
Avoid using implementation types like 'ArrayList'; use the
interface instead
Avoid using implementation types like 'Vector'; use the
interface instead
interface instead
interface instead
Avoid using implementation types like 'ArrayList'; use the interface
instead
instead
Avoid using implementation types like 'TreeMap'; use the interface
instead
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/IteratorUtils.java:17
A high number of imports can indicate a high degree of coupling
within an object.
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/SequencedHashMap.java:154
Avoid using implementation types like 'HashMap'; use the
interface instead
interface instead
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/iterators/CollatingIterator.java:49
Avoid using implementation types like 'ArrayList';
use the interface instead
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/MultiValueMap.java:78
interface instead
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/MultiValueMap.java:109
interface instead
/Users/stevehayes/commons-collections-3.2.1-src/src/java/org/apache/commons/collections/map/StaticBucketMap.java:499
interface instead


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