Java8
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Java 8 introduced several new features including lambda expressions, default methods, and the Stream API. It also replaced the PermGen memory space with Metaspace to avoid OutOfMemoryErrors. Some key language updates include support for functional interfaces, lambda expressions, default interface methods, and new collection methods like forEach and filter that work with lambda expressions. The Stream API allows functional-style operations on collections like map, reduce, and filter.
Java8
- 1. JAVA 8
- 2. OVERVIEW James Gosling The father of Java works in Typesafe Inc. for Scala Functional Programming
- 3. LANGUAGE DESIGN Static and Strongly Typed Lambda Stream API Optional Method Reference Default Method Functional Interface PermGen is replaced by MetaSpace
- 4. LIST + LAMBDA forEach() (int a, int b) -> {return a + b} (a, b) -> a + b Iterable has a new default method Lambda Expression
- 5. DEFAULT METHOD Interfaces can implement logics…
- 6. LAMBDA ->
- 7. BUT… NOT CLOSURE It should not be a variable but a constant…
- 8. FUNCTIONAL<T, R> is implemented by a lambda expression. has only one method. (except default methods) Consumer, Supplier, Function, UnaryOperator, Predicate
- 10. PREDICATE<T> used in filter() to filter a list
- 14. OPTIONAL Optional.of( your object ) o.ifPresent( do something)
- 15. METASPACE PermGen in the heap, classes loaded, are moved into the OS native memory, Metaspace Just watch the memory size of the Java process with top command No more java.lang.OutOfMemoryError: Perm Gen space -XX:MetaspaceSize