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Java 9: What’s InsideBy Dmytrii Shchadei

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What’s inside?‣ Project Jigsaw

‣ New Language Features

‣ Updates to API

‣ …

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Project Jigsaw

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‣ Project Jigsaw

‣ Module System in the Java Language

‣ Apply Module System to JDK

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JAR Hell

‣ Unexpressed Dependencies

‣ Class Shadowing

‣ Version Conflicts

‣ Complex class loading

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Java Module Heaven

‣ Explicit Dependencies

‣ Reliable Encapsulation

‣ Versioning 😭

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Modules in Practise

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JDK modularization

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JDK modularization

Compiled class

files for the base

JRE

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More JDK Changes

‣ Encapsulates most JDK internal API

‣ sun.misc.Unsafe

‣ sun.misc.Base64Encode/Decoder

‣ Remove 6 deprecated APIs (i.e. add/remove

PropertyChangeListener)

‣ Modules shared with Java EE not resolved by default

‣ New version-string format (i.e.

$MAJOR.$MINOR.$SECURITY)

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New version-string

format‣ Encapsulates most JDK internal API (i.e.

sun.*)

‣ Remove 6 deprecated APIs (i.e. add/remove

PropertyChangeListener)

‣ Modules shared with Java EE not resolved by

default

‣ New version-string format

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Jlink

‣ –module-path specifies where to find the

modules for the JDK.

‣ –add-modules adds the modules we need

‣ –limit-modules limits to just the modules that

we know our application needs (transitive

deps)

‣ –output is this directory where the run-time

image will be

Remember

Java 8

Compact

Profiles?

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Migration: Bridging

CodeModule type Origin Exports packages Can read modules

(Named) Platform Modules provided by JDK explicitly

(Named) Application Modules any JAR containing

module-info.class

on the module path

explicitly Platform

Application

Automatic

Automatic Modules any JAR without

module-info.class

on the module path

all Platform

Application

Automatic

Unnamed

Unnamed Module all JARs and classes

on the classpath

all Platform

Automatic

Application

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Migration: jdeps

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Multi-Release Jars

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JShell

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New Language

Features

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More concise try-with-resources

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Private Interface

Methods

‣ Must be implemented

‣ Can not be overridden

‣ Can only be called in a same source file

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Diamond OperatorWith Anonymous Inner Class

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Diamond OperatorWith Anonymous Inner Class

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SafeVarargs on Private

Methods

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New API

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Additions To Optional‣ Use Optional::stream to map an Optional to a

Stream.

‣ Use Optional::or to replace an empty Optional

with the result of a call returning another

Optional.

‣ With Optional::ifPresentOrElse you can do

both branches of an isPresent-if.

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Additions To Objects

‣ requireNonNullElseGet

‣ requireNonNullElse

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Additions to Process

API‣ Obtaining the PID with getPid()

‣ Obtaining process information ProcessHandle.Info

‣ Enumerating System Processes

ProcessHandle.allProcesses()

‣ Enumerating Child Processes

ProcessHandle.current().children()

‣ Triggering actions on process termination

ProcessHandle's onExit()

‣ Better Use of Hardware

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Collection Factories

All

immutable!

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Reactive StreamsJDK 9 Flow API at a Glance

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Stack-Walking APIWho called me?

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Stack-Walking APIWho called me?

‣ The forEach Method

‣ Walk the walk

why does it

not just

return the

Stream?

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Stack-Walking APIWho called me?

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Free Lunch!

‣ Multiple String Performance Improvements

‣ Better Graphics Performance

‣ Faster Compilation

‣ Better Use of Hardware