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

3.
Business

4.
Time to Market |
Speed of Delivery

5.
Economy

6.
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);
}

7.
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);
}

8.
private static Logger LOGGER = LoggerFactory
.getLogger(MyClass.class);

9.
All
models are wrong,
but some are useful.
https://en.wikipedia.org/wiki/All_models_are_wrong
George Box

10.
Pain!

11.
Suffering
Pain!

12.
I have not experienced
the pain, yet.

13.
public static String concatWithPlus(String[] values) {
String result = "";
for (int i = 0; i < values.length; i++) {
result += values[i];
}
return result;
}

14.
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();
}

15.
Java
1.4

16.
Java 5

17.
Maintainability?

18.
‘+’ vs StringBuffer
API Contract
Concatenation
Thread Safety
Level of Abstraction
Concatenation

19.
Favour
higher level of
abstraction

20.
Premature
optimisation is the
root of all evil
~ Donald Knuth

21.
Rule 1: Don’t
Rule 2: Don’t, yet
Rule 3: Profile before optimising
http://wiki.c2.com/?RulesOfOptimization

22.
YAGNI

23.
Make it work
Make it better

24.
Make it work
Make it Right
Make it Fast
http://wiki.c2.com/?MakeItWorkMakeItRightMakeItFast

25.
Java 11

26.
Red Green
Refactor
TDD

27.
/**
* 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);

28.
public List<Order>
getOrdersOfCustomer(Customer customer);
public List<OrderSummary> getOrdersOfCustomer(Customer
customer);

29.
Self Documenting Code

30.
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

31.
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

32.
Syntactic Sugar

33.
Minimise
Moving Parts

34.
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);

35.
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

36.
Favour
Declarative Code

37.
Learn Multiple
Paradigms

38.
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

39.
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

40.
What you see
is not what
you get

41.
Lazy Evaluation

42.
Understand one level
below the abstraction
you deal with

43.
Introspector.java

44.
Food pizza = new Pizza();
Person friend = new Person(“Raj");
friend.getMouth().setFood(pizza);

45.
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);

46.
Encapsulation

47.
Use checked exceptions
Judiciously

48.
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)

49.
http://zeroturnaround.com/rebellabs/the-adventurous-developers-guide-to-jvm-languages-java-scala-groovy-fantom-clojure-ceylon-kotlin-xtend/

50.
https://www.tiobe.com/tiobe-index/

51.
https://www.tiobe.com/tiobe-index/

52.
package com.nareshak.demo
data class Person(val firstName: String,
val lastName: String)

53.
package com.nareshak.demo;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class Person {
private String firstName;
private String lastName;
}

54.
package com.nareshak.demo;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class Person {
private String firstName;
private String lastName;
}

55.
package com.nareshak.demo;
import lombok.Data;
@Data
public class Person {
private String firstName;
private String lastName;
}

56.
Learn Multiple
Languages

57.
INHERITANCE
68

58.
default methods???

59.
Use features
Judiciously

60.
Strive for Simplicity
Go beyond Familiarity

61.
Evolution is the TRUE
nature of code

62.
Thank You