1. Evolving with Java - How to Remain
Relevant & Effective
Naresha K, Technical Excellence Coach | Consultant |
Agile & Cloud Transformation Catalyst
@naresha_k
https://blog.nareshak.com/

4. Business

5. Time to Market |
Speed of Delivery

6. Economy

8. About Me

9. http://nareshak.blogspot.com/

10. http://nareshak.blogspot.com/

15. Relevant?

17. Effective?

18. 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);
}

19. 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);
}

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

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

24. Pain!

25. Suffering
Pain!

26. Pain is the hammer of the gods to break
A dead resistance in the mortal’s heart
https://dhavaldalal.wordpress.com/2006/08/02/pain-and-suffering/

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

28. 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();
}

29. Java 1.4

30. Java 5

32. Maintainability?

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

34. Favour higher level
of abstraction

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

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

37. YAGNI
http://wiki.c2.com/?MakeItWorkMakeItRightMakeItFast

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

39. Red Green
Refactor
TDD

40. Java 11

41. 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

42. 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);
}
} List<Number> numbers =
Arrays.asList(1, 2, 3, 4, 5);
for(Number number : numbers) {
System.out.println(number);
}
Java 1.4
Java 5

43. Syntactic Sugar

44. Minimise Moving Parts
Imperative -> Declarative

45. Fail fast
Runtime -> Compile time

46. /**
*
* @param customer
* @return This method returns orders
* of customer
*/
public List getOrdersOfCustomer(Customer
customer);

47. /**
* 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);

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

49. Self Documenting Code

50. DRY Principle

51. 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);

52. 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

53. Declarative Code

54. Smaller Units

55. Improved Readability

56. Easy to Modify

57. Are you confident enough to
refactor?
Tests give courage

58. 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

59. 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

60. What you see is not what
you get

61. Lazy Evaluation

62. Understand one level
below the abstraction
you deal with

63. Food pizza = new Pizza();
Person friend = new Person("Ravi");
friend.getMouth().setFood(pizza);

64. Food pizza = new Pizza();
Person friend = new Person("Ravi");
friend.getMouth().setFood(pizza);
Person friend = new Person("Ravi");
Edible food = new Pizza();
friend.offer(food);

65. Encapsulation

66. public static String readTemplate(String path) {
Path templatePath = Paths.get(path);
BufferedReader bufferedReader =
Files.newBufferedReader(templatePath);
// read from bufferedReader
return "";
}

67. public static String readTemplate(String path) {
Path templatePath = Paths.get(path);
try {
BufferedReader bufferedReader =
Files.newBufferedReader(templatePath);
} catch (IOException e) {
e.printStackTrace();
}
// read from bufferedReader
return "";
}

68. Use checked exceptions
Judiciously

71. 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)

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

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

75. https://www.jetbrains.com/research/devecosystem-2018/

76. https://www.jetbrains.com/research/devecosystem-2018/

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

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

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

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

85. Overcoming the paradigm
inertia

86. Move beyond Syntax

87. Feel the pain and act upon it

88. I have not experienced the
pain, yet.

90. JPMS - Java Modules

91. Automatic Resource
Management

93. Thank You