From Mess To Masterpiece - JFokus 2017

prepare for…
From mess to masterpiece
refactoring done right
@SvenRuppert

@SvenRuppert
has been coding java since 1996
Projects in the ﬁeld of:
•Automobile-industry
•Energy
•Finance / Leasing
•Space- Satellit-
•Government / UN / World-bank
Where?
•Europe
•Asia - from India up to Malaysia
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Our journey today
what is the situation…..
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@SvenRuppert

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@SvenRuppertAt the time I started - 3 yrs ago
Codebase is > 13 years old
no test coverage
Code Lords
nearly 15% are retired soon
over 50% are since 15 yrs in the company
the developers learned Java at this project
hiring only students
the ﬁrst feeling was like ……

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@SvenRuppertAt the time I started - 3 yrs ago

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What is part of a refactoring ?
the team
the source code
the processes
the project management
the knowledge
budget and time line
infrastructure
@SvenRuppert

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What is part of a refactoring ?
the team
the source code the processes
the project management
the knowledge
budget and time line
}
}
team transformation
C-level transformation
infrastructure
@SvenRuppert

prepare for
Refactoring - the ﬁrst steps
without this you should not start
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@SvenRuppert

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@SvenRuppertﬁrst steps - Start Small

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@SvenRuppertﬁrst steps - Think Bigger

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@SvenRuppertﬁrst steps - Build a Team

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@SvenRuppertﬁrst steps - build trust

prepare for
Refactoring - the way of working
start with individual responsibility
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@SvenRuppert

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@SvenRuppertThe way of working
20% Time have time to play or try
start learning how to practice it ?
Closed Source versus Open Source
work from everywhere at your time
we started step by step

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@SvenRuppertwork from everywhere

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change your environment
use Messenger like Slack avoid mails
remote meetings with zoom
remote Pair-Programming
work async.
work at your time that is the best for you

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my „normal“ day…
working05AM to 07AM
breakfast with the family07AM to 09AM
working09AM to 12AM
playing with my son12AM to 07PM
playing with my wife07PM to 09PM
working09PM to 11PM
and yes… I need only 6h sleep ;-)

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my „normal“ day…
working05AM to 07AM
working09AM to 12AM
working09PM to 11PM
working with Asia
working with Europe
working with US

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why you should do it?20% Time
lost in daily business

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how to make it useful ?
example : POC with the team in the Mountains
for the developer
for the company
20% Time

prepare for
Refactoring - Divide your code
what is the part you are earning money with
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@SvenRuppert

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@SvenRuppertClosed- versus Open Source
Analyzing the existing Code
in our case : a lot of infrastructure…
..with this we are not earning money
we divided the
code base
dev. environment

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@SvenRuppertClosed- versus Open Source
we divided the
code base dev. environment
could write articles about it
discuss at conferences
will lead to better documentation
out of company rules
free choice of tools
higher motivation

prepare for
Refactoring - the reactions
don´t forget the team you are working with
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@SvenRuppert

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Start Learning again
for example:
functional
add a new Language
focus on a new paradigm
but not everyone want to learn
or better…. some are learning faster
reactive
this sometimes leads to …..
reactions….

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this sometimes leads to ….. reactions….
running away

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expecting something

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feeling the near end

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or only
feeling to old

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you have to deal with this
if you don´t want
to loose them
make them
happy again
How we solved
this?

prepare for
Refactoring - Projectmanagement
one size ﬁt´s all ?
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@SvenRuppert

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we are a product company
with a lot of LTS contracts
we created three streams
Consultants - play and throw away
Core Developers - collect and clean
LTS Developers - keep alive
Why ?

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Core Developer - collect and clean
LTS Developer - keep alive Why ?
some want to learn and experiment
some need more stabil environments
some did not want to change something

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LTS Developer - keep alive
Why ?
some want to learn and experiment
some need more stabil environments
some did not want to change something
amount of hours paid by the customer
rated on hours the systems are stabil
ﬁxed income - bonus based on Change Request

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LTS Developer - keep alive
SCRUM
Kanban
customer driven
roadmap driven

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SCRUM
Kanban
Consultants
LTS - Developers
Core - Developers Core - Developers
Fire
Consultants

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SCRUM
Kanban
Consultants
LTS - Developers
Core - Developers
Consultants Consultants Consultants
LTS - Developers LTS - Developers
Core - Developers Core - Developers
time based planning ﬁxed size time slots
version based dynamic size time slots

prepare for
Refactoring - Start learning again
learn how to learn together with a team again
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@SvenRuppert

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@SvenRuppertKnowledge Sharing
Consultants
LTS - Developers
Core - Developers
build a source of knowledge

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Consultants
LTS - Developers
Core - Developers
Hacking session
Articles / Blogs
Screencasts
Refactoring Sessions
POC

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How to motivate your team to do it ?
explain it !!

prepare for
Refactoring - Technologies
choose your weapons
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@SvenRuppert

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@SvenRuppertTechnical Migrations
if you ask the consultants…
to scale or change you need at least … ;-)
NoSQL
Events
Akka / Scala
Reactive
Functional
maybe ;-)

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@SvenRuppertTechnical Transformation
Swing Vaadin
HashMap Hazelcast - Map
JDBC - ResultSet Speedment - Streams
what is the right technology for your team?
what is the right order?
Java OOP Java FRP

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what is the right technology for your team?
what is the right order?
reduce complexity
scale
the team could work with
a lot more….
start with new modules ?
start with the oldest one ?
most komplex one?
… or ….

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on thing that would limit your speed…
time
number of versions
v1
v2
stabilize

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on thing that would limit your speed…
time
number of versions
v2
stabilize
delta t compared
to project lifetime

prepare for
Refactoring - Safety belt
choose your weapons
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@SvenRuppert

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@SvenRuppertQM / QS - TDD
Do you have bugs in your code ?
since years
you are
working hard
on this….
no

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@SvenRuppertQM / QS - TDD
Codebase is > 13 years old
no test coverage
how to decrease complexity?
remember….
how to start?
what is the right point to start?
how to increase the quality of the tests?

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TDD with jUnit @SvenRuppert
are you using jUnit?
assume that the following would make sense.. ;-)
public class Service { 
public int add(int a, int b){ 
if(a<2){ 
return (a+b) * -1; 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
it depends ;-)

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TDD with jUnit @SvenRuppert
public class Service { 
public int add(int a, int b){ 
if(a<2){ 
return (a+b) * -1; 
} else { 
return a+b; 
} 
} 
}
How many tests
you will need ?
for line 100% coverage 2
but will this be enough? maybe ;-)
how to ﬁnd out, what will be enough?
how to ﬁnd the right tests?
it depends ;-)

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Mutation Testing @SvenRuppert
generating the mutants and
practical TDD with Mutation Testing
running all junit tests
check the reports
write more / better tests
loop until quality target reached

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Mutation Testing - Hello World @SvenRuppert
public class Service {
public int add(int a, int b){
if (a<2) { return (a+b) * -1; }  
else { return a+b; } 
} 
} 100% Line Coverage… and…
@Test 
public void testAdd001() throws Exception { 
final int add = new Service().add(0, 0); 
Assertions.assertThat(add).isEqualTo(0); 
}
@Test 
public void testAdd002() throws Exception { 
Assertions.assertThat(add).isEqualTo(3); 
}

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Assertions.assertThat(add).isEqualTo(0);
Assertions.assertThat(add).isEqualTo(3);

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final int add = new Service().add(0, 0);
>> Generated mutations Killed 3

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>> Generated mutations Killed 3

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Mutation Testing - in short words @SvenRuppert
mutation testing is an add on to normal jUnit TDD
tools are supporting it well
generating and running all tests are time consuming
but most important
will eﬀect your project structure

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Mutation Testing - Lesson Learned @SvenRuppert
mutation tests are often leading to
…cleaner code compared to jUnit only

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public static ﬁnal String[] discardCommonPreﬁx(String a, String b) {
String[] ret = { a, b };
int l = a.length() < b.length() ? a.length() : b.length();
for (int i = 0; i < l; i++) {
if (a.charAt(i) == b.charAt(i)) {
if (i + 1 < l) { ret[0] = a.substring(i + 1); ret[1] = b.substring(i + 1); }
else {
if (a.length() < b.length()) { ret[0] = ""; ret[1] = b.substring(i + 1); }
if (a.length() == b.length()) { ret[0] = ""; ret[1] = „"; }
if (a.length() > b.length()) { ret[0] = a.substring(i + 1); ret[1] = „"; }
}
} else break;
}
return ret;
}

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public String[] discardCommonPrefix(String a, String b) {
final String[] ret = new String[2];
int l;
if (a.length() < b.length()) { l = a.length(); }
else { l = b.length(); }
int position = 0;
for (; position < l; position++) {
final char charA = a.charAt(position);
final char charB = b.charAt(position);
if (charA != charB) { break; }
}
if (position >= a.length()) { ret[0] = ""; }
else { ret[0] = a.substring(position); }
if (position >= b.length()) { ret[1] = ""; }
else { ret[1] = b.substring(position); }
return ret;
}

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Version 1 Version 2
for {
if {
if
else {
if
if
if
}
} else
}
if else
for {
if
}
if else
if else

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Example of useless Code @SvenRuppert

Functions
how use Functions…
@SvenRuppert

Functions - Java8
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@SvenRuppert

Functions - Java8
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@SvenRuppert

Functions - Java8
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@SvenRuppert

prepare for
Refactoring - Design Pattern
start developing design pattern again
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@SvenRuppert

NestedBuilder - The Beginning
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@SvenRuppert

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@SvenRuppert
Car car = Car.newBuilder() 
.withEngine(engine) 
.withWheelList(wheels) 
.build();
Engine engine = Engine.newBuilder().withPower(100).withType(5).build();
Wheel wheel1 = Wheel.newBuilder().withType(2).withColour(3).withSize(4).build();  
Wheel wheel2 = Wheel.newBuilder().withType(2).withColour(3).withSize(4).build(); 
Wheel wheel3 = Wheel.newBuilder().withType(2).withColour(3).withSize(4).build();
List<Wheel> wheels = new ArrayList<>(); 
wheels.add(wheel1); 
wheels.add(wheel3);}

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@SvenRuppert
.build();
wheels.add(wheel3);

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@SvenRuppert
.build();
//List<Wheel> wheels = new ArrayList<>(); 
// wheels.add(wheel1); 
// wheels.add(wheel2); 
// wheels.add(wheel3);
List<Wheel> wheelList = WheelListBuilder.newBuilder() 
.withNewList() 
.addWheel(wheel1) 
.build(); //more robust if you add tests at build()
}
}
how to combine ?
wheels.add(wheel3);

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@SvenRuppert
.build();
List<Wheel> wheelList = WheelListBuilder.newBuilder() 
.withNewList() 
.build();
}
}
how to combine ?

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@SvenRuppert
.build();
// Wheel wheel1 = Wheel.newBuilder().withType(2).withColour(3).withSize(4).build();  
// Wheel wheel2 = Wheel.newBuilder().withType(2).withColour(3).withSize(4).build(); 
// Wheel wheel3 = Wheel.newBuilder().withType(2).withColour(3).withSize(4).build();
// List<Wheel> wheelList = WheelListBuilder.newBuilder() 
.withNewList() 
.build();
List<Wheel> wheels = wheelListBuilder 
.addWheel().withType(1).withSize(2).withColour(2).addWheelToList() 
.build();

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@SvenRuppert
.build();
.build();
WheelBuilder
WheelListBuilder

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@SvenRuppert
.build();
.build();
now we have to combine all
.addEngine().withPower(100).withType(5).done() 
.addWheels() 
.done() 
.build();

NestedBuilder - The Pattern
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@SvenRuppert
public abstract class NestedBuilder<T, V> {
protected T parent;
public abstract V build()
public <P extends NestedBuilder<T, V>> P  
withParentBuilder(T parent) { 
this.parent = parent; 
return (P) this; 
}
parent will connect itself…

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@SvenRuppert
public abstract class NestedBuilder<T, V> {
public T done() {
Class<?> parentClass = parent.getClass();
try { 
V build = this.build(); 
String methodname = "with" + build.getClass().getSimpleName(); 
Method method = parentClass.getDeclaredMethod( 
methodname, build.getClass()); 
method.invoke(parent, build); 
} catch (NoSuchMethodException  
| IllegalAccessException | InvocationTargetException e) { 
e.printStackTrace(); 
}
}
connect itself with parent

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@SvenRuppert
the basic steps in short words
the Parent-Builder will hold the Child-Builder
the Parent-Builder will have a addChild - Method
the Child-Builder will extend the NestedBuilder
the rest could be generated with a  
default Builder-Generator

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@SvenRuppert
public class Parent { 
private KidA kidA; 
private KidB kidB; 
//snipp..... 
public static ﬁnal class Builder { 
private KidA kidA; 
private KidB kidB; 
// to add manually 
private KidA.Builder builderKidA = KidA.newBuilder().withParentBuilder(this); 
private KidB.Builder builderKidB = KidB.newBuilder().withParentBuilder(this); 
 
public KidA.Builder addKidA() { 
return this.builderKidA; 
} 
public KidB.Builder addKidB() { 
return this.builderKidB; 
} 
//---------
connect itself with child
switch to Child-Builder

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@SvenRuppert
only extends on Child-Builder
public static ﬁnal class Builder  
extends NestedBuilder<Parent.Builder, KidA> {

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@SvenRuppert
Parent build = Parent.newBuilder() 
 
.addKidA().withNote("A").done() 
.addKidB().withNote("B").done() 
 
.build(); 
System.out.println("build = " + build);
and a child could be a parent in the same time
Parent build = Parent.newBuilder() 
.addKidA().withNote("A")
.addKidB().withNote("B").done()
.done() 
.build();
System.out.println("build = " + build);

Refactoring example
based on Java8
@SvenRuppert

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@SvenRuppertJava8 - Functional Interfaces - Example
typical legacy implementation

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typical legacy implementation

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Sourcecode is on github

Interpreter - pre Java8
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@SvenRuppert

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@SvenRuppert

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@SvenRuppert

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@SvenRuppert

Interpreter - Java8 - Java9
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@SvenRuppert

Interpreter - Java8 - Java9
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@SvenRuppert
Main Idea - DataStructure to Function

Memoizing
partial cache-ing ?
@SvenRuppert
full example and code
http://www.functional-reactive.org/

prepare for
Refactoring - Clean your code
nano refactoring on language level
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@SvenRuppert

clean your code @SvenRuppert
delete JavaDoc
use ﬁnal for Attributes as much as possible
replace loops with streams
extract Functional Interfaces
remove anonymous classes
use everywhere the same language level
Why ?

clean your code @SvenRuppert
delete JavaDoc
use ﬁnal for Attributes as much as possible
replace loops with streams
extract Functional Interfaces
remove anonymous classes
use everywhere the same language level
Why ?
know the part you want to refactor
homogeneous sources are better for machines

prepare for
Refactoring - Summary
the full picture
102
@SvenRuppert

Refactoring - Summary
103
@SvenRuppert
prepare your team
change the way of working
work on your project management
build your safety belt - mutation testing
divide and conquer - @Inject
build design pattern again
extract cross functionality - Proxy's
clean your code

prepare for
Management - Summary
the full picture for the C-Level
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@SvenRuppert

Management - Summary
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@SvenRuppert
Now it is time to relax again ;-)
Problem solved !

Summary
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@SvenRuppert
places to read more about it
www.functional-reactive.org
www.java-9.org
or contact me ;-) @SvenRuppert
Thank You !!!

From Mess To Masterpiece - JFokus 2017

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From Mess To Masterpiece - JFokus 2017