Java8 新特性

Java8 new features
Java Language Specifioon

• Lamada Expression

enable you to treat functionality as a method argument, or code as data.

and express interface with one-method more compactly

• Method Reference

provide easy-to-read lambda expressions for methods that already have a name.eg: System.out::println

• Default method

enable new functionality to be added to the interfaces of libraries which fuck abstract class

• Repeating Annotations

provide the ability to apply the same annotation type more than once to the same declaration or type use.

• Type Annotations

provide the ability to apply an annotation anywhere a type is used, not just on a declaration.

Used with a pluggable type system, this feature enables improved type checking of your code.

• Improved type inference.
• Method parameter reflection

Collections

• Class in the new java.util.stream package provide a Stream API to support functional-style operations on streams of

　　　elements.The Stream API is integrated into the Collection API,which enables bulk operations on collections,such as

        sequential or parallel map-reduce transformations

• Performance Improvement for HashMaps with Key Collisions.

Internationalization

• Unicode Enhancements ,including support for Unicode 6.2.0
• Adoption of Unicode CLDR Data and the java.locale.providers System property
• New Calendar and Locale APIS
• Ability to Install a Custom Resource Bundle as an Extension
  

Date-Time package

• a new set of packages that provide a comprehensive date-time model.

Java Mission Control --need to learn

HotSpot

• HardWare intrinsics 
• Removal of PermGen
• Default Methods in the Java Programming Language are supported by the byte code instructions for method invocation

Java XML --JAXP

Concurrency

• Classes and interfaces have been added to the java.util.concurrent package.

• Methods have been added to the java.util.concurrent.ConcurrentHashMap class to support aggregate operations based on the newly added streams facility and lambda expressions.

• Classes have been added to the java.util.concurrent.atomic package to support scalable updatable variables.

• Methods have been added to the java.util.concurrent.ForkJoinPool class to support a common pool.

• The java.util.concurrent.locks.StampedLock class has been added to provide a capability-based lock with three modes for controlling read/write access.

Java.lang And Java.util Packages

• Parallel Array Sorting

• Standard Encoding and Decoding Base64

• Unsigned Arithmetic Support

IO And NIO

• New SelectorProvider implementation for Solaris based on the Solaris event port mechanism. To use, run with the system property java.nio.channels.spi.Selectorset to the value sun.nio.ch.EventPortSelectorProvider.

• Decrease in the size of the <JDK_HOME>/jre/lib/charsets.jar file

• Performance improvement for the java.lang.String(byte[], *) constructor and thejava.lang.String.getBytes() method.