Java 8 hands on

Lambda Expression

• short form replacement for anonymous classes.
• simplifying the implementation of functional interfaces.
• functional interfaces: Interfaces with only one method declaration.
• functional interfaces were implementing using
  • A class that implements this interface.
  • anonymous class for that interface.
• lambda expression is designed to support multicore processor architecture (don’t know how).

benefits of Lambda

• concise implementation
• Method references and constructor references.
• Reduced runtime overhead compared to anonymous classes

Syntax

(formal parameter list) -> { expression or statements }

• A lambda expression has an implicit target type associated with it because an interface type is not explicitly specified.
• The target type of a lambda conversion must be a functional interface.
• Lambda expressions can be used only in contexts in which the target type can be inferred. Such contexts are:
  • A variable declaration
  • An assignment
  • A return statement
  • An array initializer
  • Method or constructor arguments
  • A lambda expression body
  • A ternary conditional expression
  • A cast expression
• A lambda expression body must not throw more exceptions than specified in the throws clause of the functional interface method. If a lambda expression body throws an exception, the throws clause of the functional interface method must declare the same exception type or its supertype.
• To be continued .............. you can check below code examples in order and try to understand the idea behnid each example.

Examples in order

4. Hello
5. HelloCallable
6. HelloRunnable
7. LambdaWithVariables
8. ArrayInitializer
9. FunctionalInterfaceWithArrayAsParameter
10. LambdaInGUI
11. ConditionalExpression
12. SameLambdaDifferentType
13. InnerLambda
14. ExceptionHandling
15. Ambiguity
16. Inferring
17. This
18. MethodReference
19. ConstructorReference
20. VirtualExtensionMethods
21. PrintList

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Useful Links

https://leanpub.com/whatsnewinjava8/read http://www.oracle.com/technetwork/articles/java/lambda-1984522.html http://baddotrobot.com/blog/2014/02/18/method-references-in-java8/ http://docs.oracle.com/javase/tutorial/java/javaOO/methodreferences.html http://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html