The document discusses strategies for software developers to remain relevant and effective in Java, emphasizing aspects like maintainability, the importance of abstraction, and evolution in coding practices from Java 1.4 to Java 11. It presents various code examples to illustrate best practices, such as using streams and lambda expressions, and highlights principles like YAGNI (You Aren't Gonna Need It) and the DRY (Don't Repeat Yourself) principle. Additionally, it touches on topics such as encapsulation, lazy evaluation, and the notion that understanding the underlying abstractions can enhance coding skills.

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