JAVA SE 8 Features

JAVA 8 Features List:

1. Virtual  Extension Methods: Interface Default Methods 
2. Virtual  Extension Methods: Interface Static Methods
3. "Class Wins" Rule
4. Functional Interface, @FunctionalInterface
5. Enhanced Type Inference
6. Lambda Expressions
7. Functional Interfaces - Function,Consumer,Supplier,Predicate etc
8. Method References
9. Constructor References
10. Stream API
11. Stream Primitive Specilizations
12. Date & Time API
13. Collectors
14. StringJoiner
15. Collections API Enhancements
16. Concurrency Utils Enhancements
17. java.util.concurrent.atomic Enhancements
18. Collections Bulk Data Operations
19. StampedLock
20. Fork/Join Framework Enhancements
21. Internal Iteration
22. Parallel Array Operations
23. Parallel Collection Operations
24. Parallel Stream Operations
25. Arrays Spliterators
26. Collections Spliterators
27. Streams Spliterators
28. Optional
29. Type Annotations
30. Method Parameter Reflection
31. Repeating Annotations
32. Base64 Encoding and Decoding
33. IO and NIO2 Enhancements 
34. Nashorn JavaScript Engine
35. javac Enhancements
36. JVM Changes
37. Java 8 Compact Profiles: compact1,compact2,compact3
38. JDBC 4.2
39. JAXP 1.6
40. Java DB 10.10
41. Networking
42. Java Security Changes

Now we'll discuss each topic in detail.

Optional:

• Optional is a final Class in java.util package
• It is an alternative to "null" value
• It is used to avoid "NullPointerException"

Example-1:

package com.way2it.java8.optional;

import java.util.Optional;

public class OptionalTest {

public static void main(String[] args) {

    Optional<String> optional = Optional.of("Rams");

        System.out.println("optional.isPresent() : " + optional.isPresent()); 

        System.out.println("optional.get() : " + optional.get());             

        System.out.println("optional.orElse(\"Posa\") : " + optional.orElse("Posa"));    

        optional.ifPresent((s) -> System.out.println(s.charAt(0)));   

}

} 

Output:

optional.isPresent() : true

optional.get() : Rams

optional.orElse("Posa") : Rams

R

Example-2:-

package com.way2it.java8.optional;
import java.util.Optional;
public class OptionalTest2 {
public static void main(String[] args) {
        Optional<String> optional = Optional.empty();
        System.out.println(optional);
        System.out.println(optional.isPresent());
     
        Optional<String> optional2 = Optional.ofNullable(null);
        System.out.println(optional2);
        System.out.println(optional2.isPresent());
     
        String value = "Rams";
        Optional<String> optional3 = Optional.ofNullable(value);
        System.out.println(optional3);
        System.out.println(optional3.isPresent());
    }
}

Output:

Optional.empty
false
Optional.empty
false
Optional[Rams]
true