Slides from my Java2Days 2020 talk - "Evolving with Java - How to Remain Effective". Developers find themselves in need to continually update themselves with the rapidly changing technologies to remain relevant and deliver value. However, by keeping a few things in mind and with certain practices, this can be a pleasant experience. In this presentation, I share my experiences learning and evolving with Java in the last 15+ years. The ideas presented are generic enough to be applicable for people using any technology stack. However, the code examples are in Java/ JVM languages. We start by understanding the importance of gradual improvement. To keep motivated for continuous improvement, in my experience, responsiveness is a vital element. I share my experience of how to increase your responsiveness. To be able to change/ experiment continuously in our code, we need to ensure that we don't break anything. We explore the necessary techniques to achieve safety. Often we mistakenly consider lack of familiarity as complexity. We explore options to come out of this confusion. We then touch upon the impact of learning paradigms and multiple languages available on the JVM. Finally, we touch upon another important aspect of continuous improvement that is unlearning. We conclude the session by summarising the principles.

1. Evolving with Java - How to
Remain Effective
Naresha K
@naresha_k
https://blog.nareshak.com/

2. About me
Developer, Architect &
Tech Excellence Coach
Founder & Organiser
Bangalore Groovy User
Group

5. Business

6. Time to Market |
Speed of Delivery

8. Economy

9. public static void main(String[] args) {
List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
List<Integer> result = numbers.stream()
.map(ParallelStreams::computeHeavyArithmetic)
.collect(Collectors.toList());
System.out.println(result);
}
public static void main(String[] args) {
List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
List<Integer> result = numbers.parallelStream()
.map(ParallelStreams::computeHeavyArithmetic)
.collect(Collectors.toList());
System.out.println(result);
}

10. public static void main(String[] args) {
List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
List<Integer> result = numbers.stream()
.map(ParallelStreams::computeHeavyArithmetic)
.collect(Collectors.toList());
System.out.println(result);
}
public static void main(String[] args) {
List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
List<Integer> result = numbers.parallelStream()
.map(ParallelStreams::computeHeavyArithmetic)
.collect(Collectors.toList());
System.out.println(result);
}

12. private static Logger LOGGER = LoggerFactory
.getLogger(MyClass.class);

14. All
models are wrong,
but some are useful.
https://en.wikipedia.org/wiki/All_models_are_wrong
George Box

15. Pain!

16. Suffering
Pain!

17. I have not experienced
the pain, yet.

18. public static String concatWithPlus(String[] values) {
String result = "";
for (int i = 0; i < values.length; i++) {
result += values[i];
}
return result;
}

19. public static String concatWithStringBuffer(String[] values) {
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < values.length; i++) {
buffer.append(values[i]);
}
return buffer.toString();
}

20. Java
1.4

21. Java 5

23. Maintainability?

24. ‘+’ vs StringBuffer
API Contract
Concatenation
Thread Safety
Level of Abstraction
Concatenation

25. Favour
higher level of
abstraction

26. Premature
optimisation is the
root of all evil
~ Donald Knuth

27. Rule 1: Don’t
Rule 2: Don’t, yet
Rule 3: Profile before optimising
http://wiki.c2.com/?RulesOfOptimization

28. YAGNI

29. Make it work
Make it better

30. Make it work
Make it Right
Make it Fast
http://wiki.c2.com/?MakeItWorkMakeItRightMakeItFast

31. Java 11

32. Red Green
Refactor
TDD

33. /**
* This method returns orders of customer
* @param customer Customer whose orders to be fetched
* @return List containing Order objects of the
* specified Customer
*/
public List getOrdersOfCustomer(Customer customer);

34. public List<Order>
getOrdersOfCustomer(Customer customer);
public List<OrderSummary> getOrdersOfCustomer(Customer
customer);

35. Self Documenting Code

36. public static void main(String[] args) {
List numbers = Arrays.asList(1, 2, 3, 4, 5);
Iterator iterator = numbers.iterator();
while (iterator.hasNext()) {
Number number =
(Number) iterator.next();
System.out.println(number);
}
}
Java
1.4

37. public static void main(String[] args) {
List numbers = Arrays.asList(1, 2, 3, 4, 5);
Iterator iterator = numbers.iterator();
while (iterator.hasNext()) {
Number number =
(Number) iterator.next();
System.out.println(number);
}
}
Java
1.4
List<Number> numbers =
Arrays.asList(1, 2, 3, 4, 5);
for(Number number : numbers) {
System.out.println(number);
}
Java 5

38. Syntactic Sugar

39. Minimise
Moving Parts

40. List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
int sumOfSquaresOfEvenNumbers = 0;
for (Integer number : numbers) {
if(number % 2 == 0) {
sumOfSquaresOfEvenNumbers += number * number;
}
}
System.out.println(sumOfSquaresOfEvenNumbers);

41. List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
int sumOfSquaresOfEvenNumbers = 0;
for (Integer number : numbers) {
if(number % 2 == 0) {
sumOfSquaresOfEvenNumbers += number * number;
}
}
System.out.println(sumOfSquaresOfEvenNumbers);
Predicate<Integer> isEven = (number) -> number % 2 == 0;
Function<Integer, Integer> square = (number) -> number *
number;
List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
Integer sum = numbers.stream()
.filter(isEven)
.map(square)
.collect(Collectors.
summingInt(Integer::intValue));
System.out.println(sum);
Java 8

42. Favour
Declarative Code

43. Learn Multiple
Paradigms

44. Predicate<Integer> isEven = (number) -> number % 2 == 0;
Function<Integer, Integer> square = (number) ->
number * number;
List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
Integer result = numbers.stream()
.filter(isEven)
.map(square)
.findFirst().orElse(-1);
System.out.println(result);
Java 8

45. Predicate<Integer> isEven = (number) -> number % 2 == 0;
Function<Integer, Integer> square = (number) ->
number * number;
List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
Integer result = numbers.stream()
.filter(isEven)
.map(square)
.findFirst().orElse(-1);
System.out.println(result);
List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);
int suqareOfFirstEvenNumber = -1;
for (Integer number : numbers) {
if(number % 2 == 0) {
suqareOfFirstEvenNumber += number * number;
break;
}
}
System.out.println(suqareOfFirstEvenNumber);
Java 8

46. What you see
is not what
you get

47. Lazy Evaluation

48. Understand one level
below the abstraction
you deal with

49. Introspector.java

50. Food pizza = new Pizza();
Person friend = new Person(“Raj");
friend.getMouth().setFood(pizza);

51. Food pizza = new Pizza();
Person friend = new Person(“Raj");
friend.getMouth().setFood(pizza);
Person friend = new Person(“Raj");
Edible food = new Pizza();
friend.offer(food);

52. Encapsulation

53. Use checked exceptions
Judiciously

55. 55
Most people talk about Java the language,
and this may sound odd coming from me,
but I could hardly care less. At the core of
the Java ecosystem is the JVM.
- James Gosling,
Creator of the Java Programming Language(2011, TheServerSide)

56. http://zeroturnaround.com/rebellabs/the-adventurous-developers-guide-to-jvm-languages-java-scala-groovy-fantom-clojure-ceylon-kotlin-xtend/

57. https://www.tiobe.com/tiobe-index/

58. https://www.tiobe.com/tiobe-index/

63. package com.nareshak.demo
data class Person(val firstName: String,
val lastName: String)

64. package com.nareshak.demo;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class Person {
private String firstName;
private String lastName;
}

65. package com.nareshak.demo;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class Person {
private String firstName;
private String lastName;
}

66. package com.nareshak.demo;
import lombok.Data;
@Data
public class Person {
private String firstName;
private String lastName;
}

67. Learn Multiple
Languages

68. INHERITANCE
68

69. default methods???

70. Use features
Judiciously

72. Strive for Simplicity
Go beyond Familiarity

73. Evolution is the TRUE
nature of code

74. Thank You