Presentation given at Jazoon 2012 on syntactical elements of new Java language enhancements, as well as covering DSL's, aspects and annotations.

1. Syntactic Salt and Sugar
James Gould
Alex Holmes
Verisign
205

2. Alex
2

3. Jim
3

4. Introduction
4

5. Format
Discuss 5 Syntactic Elements
> >
Lead discussion of each Element
Introduce newer Elements
– – –
Identify Good
Identify Bad
Participation is encouraged!
>
5

6. AGENDA
> DSL
> Project Lambda
> AOP 2
> CDI
> Grab Bag
6

7. AGENDA
> DSL
> Project Lambda
2
> AOP
> CDI
> Grab Bag
7

8. omain specific language
Noun: a computer programming language
of limited expressiveness focused on
a particular domain.

9. Rich languages

10. Domain specific language

11. DSL examples
ELECT * FROM STATION WHERE LAT_N > 39.7;

12. Domain model

13. Grammatical Elements of a DSL
operators +
verbs nouns separators
deposit account () {} [] . -> => =
withdraw amount < > ! ~ ? : ==
++ || -- *=
<<< % ^ ; ,
%= && >= -1
>>>= // #

14. Internal DSL
An internal DSL is a DSL
represented within the syntax of
a general-purpose language.
It's a stylized use of that
language for a domain-specific Excerpt from Martin
Fowler’s book “Domain
purpose. Specific Languages”,
published by Addison-
Wesley

15. Java internal DSL
15

16. Java internal DSL

17. External DSL
An external DSL is a domain-
specific language represented in a
separate language to the main
programming language it's
working with. This language may
use a custom syntax, or it may Excerpt from Martin
Fowler’s book “Domain
follow the syntax of another Specific Languages”,
published by Addison-
Wesley
representation such as XML.

18. External DSL for ATM
d -> :a(0.95) :chk(12345)
What do “d”, “a” and “chk” represent?
What’s with the obfuscated syntax?
Where is the language documented?
YALTL – Yet another language to learn

19. Just call me Sherlock

20. Re-worked DSL grammar
deposit amount 0.95
into checking 12345

21. DSL Sugar
diomatic way to communicate with domain experts
an be used by non-programmers
elf-documenting
21

22. DSL Salt
SL syntax can quickly become salty
o you really need a DSL?
upporting a DSL is labor-intensive
22

23. AGENDA
> DSL
> Project Lambda
2
> AOP
> CDI
> Grab Bag
23

24. Project Lambda : Introduction
> Included in Java 8
> Defined in JSR-335
– Lambda Expressions
– Default Methods
24

25. Project Lambda : Lambda Expressions
public class Calculator {
ublic class Calculator {
static interface Calculate {
int calc(int op1, int op2);
static interface Calculate {
}
int calc(int op1, int op2);
public static void main(String... args) {
} Calculate addition = (op1, op2) -> op1 + op2;
public static void main(String... args) {
System.out.println("Addition = " + addition.calc(10, 20));
Calculate addition = new Calculate() {
Calculate multiply = (op1, op2) -> op1 * op2;
public int calc(int op1, int op2) {
System.out.println("Multiply = " + multiply.calc(10, 20));
return op1 + op2;}};
}
} System.out.println("Addition = " + addition.calc(10, 20)); 25

26. Project Lambda : Type Targeting
> How “Calculate addition = (op1, op2) -> op1 + op2;” works?
– Type expression is inferred by type expected in context
– Calculate is a Functional Interface
– Expression compatible to Function Interface
 Interface is Functional Interface
 Expression has same number of parameters
 Expression return is compatible
 Expression exception thrown is allowed by Interface
> Lambda’s are strongly typed
26

27. Project Lambda : Type Targeting Sample
ublic class HelloWorld {
public static void main(String... args) throws Exception {
Callable<Void> helloCall =
() -> {System.out.println("Hello World!"); return null;};
Runnable helloRun =
() -> {System.out.println("Hello World!");};
27
helloCall.call();

28. Lambda’s and Collections
raditional iteration: ewritten for lambda’s:
or (Car c : cars) { ars.forEach(c -> c.setColor(RED));
c.setColor(RED); arallelized:
ars.parallel()
.forEach(c -> c.setColor(RED));
28

29. Project Lambda : Lambda Expression Sugar
nonymous addition = (op1, op2)in aop1 + op2;
Calculate Inner Classes done -> clean way
Calculate addition = new Calculate() {
public int calc(int op1, int op2) {
return op1 + op2;
}};
atches feature of other languages
C#, C++, Ruby, Python, JavaScript, …
Take advantage of multicore processors
Mark Reinhold – “the real reason is multicore
processors; the best way to handle them is with 29
Lambda”

30. Project Lambda : Lambda Expression Salt
ark Reinhold – “Some would say adding
Lambda expressions is just to keep up with the
cool kids, and there’s some truth in that”
ava as a Object Oriented language
o you want Anonymous Inner Classes on
steroids?
ack of code clarity
30

31. Project Lambda : Default Methods
nterface A {
void execute() default {
System.out.println("A.execute()");
}
lass ClassA implements A {
lassA classA = new ClassA(); 31

32. Project Lambda : Default Methods
nterface A {
void execute() default {
System.out.println("A.execute()");
}
nterface B extends A {
void execute() default {
System.out.println(“B.execute()");
32
}

33. Project Lambda : Default Methods
nterface A {
void execute() default {
System.out.println("A.execute()");
}
nterface B {
void execute() default {
System.out.println(“B.execute()");
}
lass ClassHuh implements A, B { 33
void execute() {

34. Project Lambda : Default Methods and Lambda
nterface A {
void execute() default {
System.out.println("A.execute()");
}
nterface B extends A {
void execute() default {
System.out.println(“B.execute()");
}
void execute2();
34
nterface C extends A, B {}

35. Project Lambda : Default Methods Sugar
inally able to add code to interfaces!
35

36. Project Lambda : Default Methods Salt
dding multiple inheritance to Java
ixing Default Methods and Lambda Expressions
adds more confusion
36

37. AGENDA
> DSL
> Project Lambda
2
> AOP
> CDI
> Grab Bag
37

38. AOP 2 : Introduction
spect Oriented Programming (AOP)
nnotation Oriented Programming (AOP)
2
OP
38

39. AOP 2 : Aspect Oriented Programming
> When should aspects be used?
– By container?
By container?
– Extraneous functions?
Extraneous functions?
– Semantics of the language?
 A = B?
= B?
39

40. AOP 2 : Annotation Oriented Programming
> Annotations designed in similar goals as AOP
– Special markers to classes, methods, and fields
– Processed by libraries and tools
> Everything seems to be annotated now!
40

41. AOP 2 : Annotation Oriented Programming Sample
@Data
RequiredArgsConstructor
public class Sample {
private final int age;
@NonNull private String name;
EqualsAndHashCode
}
ToString
ublic class Sample {
Sample sample = new Sample(21, “James”);
@Getter private final int age;
assert ( sample.getAge() == 21);
assert ( sample.getName().equals(“James”));
sample.setName(“Jim”);@Setter private String name;
@NonNull @Getter
System.out.println(“sample = “ + sample);
“sample = Sample(age=21, name=Jim) 41

42. AOP 2 : Annotations Sugar
Communication with compiler
@Override, @Deprecated, @SuppressWarnings
Communication with frameworks
Java Persistence API, Spring
42

43. AOP 2 : Annotations Salt
Configuration
Added Dependencies
Used for code generation
43

44. 2 2
AOP : AOP
> Annotations and aspects together is a natural fit
– Annotations provide meta-data
– Aspects to drive cross-cutting logic based on Annotations
44

45. AOP 2 : Java EE Interceptors
ublic class PrintInterceptor {
@AroundInvoke
public Object execute(InvocationContext ctx) throws Exception {
System.out.println("Intercepting method " +
ctx.getMethod().getDeclaringClass().getName() + ":" +
ctx.getMethod().getName());
Object result = ctx.proceed(); 45
return result;

46. AOP 2 : What is This?
Procedure(name = "Account.deposit")
ublic void deposit (
@In(Types.NUMERIC) final Long accountId,
@In(Types.NUMERIC) final Long locationId,
@In(Types.NUMERIC) final BigDecimal amount,
@In(Types.TIMESTAMP) final Date transactionDate,
@Out(Types.NUMERIC) Ref<BigDecimal> balance) { 46

47. AGENDA
> DSL
> Project Lambda
2
> AOP
> CDI
> Grab Bag
47

48. Changing Landscape of Dependency Injection

49. Huh?

50. JSR-330 + JSR-299 Compared

51. JSR-330 Annotations
• @Inject
• @Named
• @Provider
• @Qualified
• @Scope
• @Singleton

52. Basic Injection

53. Named Injections

54. Qualifiers

55. Pop Quiz
Question: Do both garage instances
refer to the same object?
Answer: No, the default scoping in
JSR-330 is “@Dependent”
55

56. Scopes

57. JSR-299 – Context Dependency Injection
• Uses JSR-330 as foundation
• Adds Java EE-specific extensions
• Producers
• Decorators
• Interceptor enhancements

58. JSR-299 – Additional Scopes
built-in scopes:
RequestScoped
SessionScoped
ApplicationScoped
ConversationScoped

59. Pop Quiz

61. CDI Extensions

62. CDI Sugar
tandards for Dependency Injection
nnotation-driven injection, decorators, interceptors
xtensible SPI
62

63. CDI Salt
hy are there 2 standards?
ack of Java SE DI support
o dynamic DI injection
63

64. AGENDA
> DSL
> Project Lambda
2
> AOP
> CDI
> Grab Bag
64

65. Binary Literals and Underscores

66. Handling multiple exceptions

67. Multi-Catch

68. Resource cleaning

69. Try-with-resources

70. Strings in switch

71. Diamonds (are a geek’s best friend)

72. Java 7 Language Enhancements: Sugar or Salt?
72

73. James Gould verisigninc.com
Verisign jgould@verisign.com
Alex Holmes verisign.com
Verisign alholmes@verisign.com