Introduction to Java 8

Biggest upgrade to the Java programming model ever

Over 50 new features

Goals:

• Better developer productivity 
• More reliable code 
• Better utilisation of multi-core/processor systems 

Lambda Expressions & Virtual Extension Methods

Autoconf-Based Build System

Lambda-Form Representation for Method Handles

Compact Profiles

Prepare for Modularization

Leverage CPU Instructions for AES Cryptography

Nashorn JavaScript Engine

Mechanical Checking of Caller-Sensitive Methods

Document JDK API Support and Stability

Reduce Cache Contention on Specified Fields

Remove the Permanent Generation

Retire Some Rarely-Used GC Combinations

Enhanced Verification Errors

Reduce Class Metadata Footprint

Small VM

Fence Intrinsics

Launch JavaFX Applications

Generalized Target-Type Inference

Annotations on Java Types

DocTree API

Add Javadoc to javax.tools

Remove the Annotation-Processing Tool (apt)

Access to Parameter Names at Runtime

Repeating Annotations

Enhance javac to Improve Build Speed

DocLint

Parallel Array Sorting

Bulk Data Operations for Collections

Enhance Core Libraries with Lambda

Charset Implementation Improvements

javax.lang.model Implementation Backed by Core Reflection

Base64 Encoding & Decoding

Reduce Core-Library Memory Usage

Date & Time API

Concurrency Updates

JDBC 4.2

And thats not even all of it...

Lambda Expressions

Functional Interfaces

Method References

Default Methods

Streams

Type Annotations

Modularisation

Date-Time

Misc

The complete list of new functional interfaces can be found in java.util.function

List.Stream()
// from a list

(There are lots)

map.values().Stream()
// from a map

"string".chars()
// from a string

Stream.of("a", "b", "c")
// from elements

Stream.iterate(0, i -> i+1)
// iteration

Stream.generate(() -> Math.random())
// generation

Stream.builder().add("one").build()
// building

Stream.of("a1", "a2", "a3")
    .findFirst()
    .ifPresent(System.out::println);  // a1

IntStream.range(1, 4)
    .forEach(System.out::println);

// 1
// 2
// 3

Supplier<Stream<String>> streamSupplier =
    () -> Stream.of("d2", "a2", "b1", "b3", "c")
            .filter(s -> s.startsWith("a"));

streamSupplier.get().anyMatch(s -> true);   // ok
streamSupplier.get().noneMatch(s -> true);  // ok

• Previously annotations could only be applied to declarations.

• With Java 8, annotations can now also be written on any use of a type such as types in declarations, generics, and casts:

@Encrypted String data;
List<@NonNull String> strings;
myGraph = (@Immutable Graph) tmpGraph;

" Java 8 introduces a new concept called, Compact Profiles, which enable reduced memory footprint for applications that do not require the entire Java platform "

Long standing issue is the inadequate support for the date and time:

 - Not thread-safe, potential concurrency issues.

- Unintuitive API design in some cases. 

- Led to the popularity of third-party libraries (Joda-Time).

Found in java.time

• All core libraries have been modernised with lambdas to improve performance and demonstrate best practices. 

• Mechanism to retrieve parameter names at runtime via core reflection.

       - Improve IDE capabilities 

• Parallel array sorting: java.util.Arrays.parallelSort() ​

• Base64 encoding and decoding: java.util.Base64.Encoder and java.util.Base64.Decoder

• Previously the JDK shipped with a JavaScript scripting engine based on Mozilla Rhino, this has been rewritten from the ground up, now called Nashorn.

• Retired rarely used garbage collection combinations.