CodeOne 2018 - Day Four talks

Here are my notes from the talks I attended on Day Four at CodeOne (the successor toJavaOne). We have a summary report on our 4 highlights from Oracle CodeOne and you can find Monday’s here, Tuesday’s here, and Wednesday’s here.

I have added my takeaways at the end of each. Any mistakes or omissions are mine. Please add comments if you would like any items expanded.

The Future of Java SE [DEV6323]

Aim to be open, evolving, nimble, scalable
Adding very easy, changing very hard (and removing)
JDK9 first release to remove stuff.
Recovered new release model for JDK and slippage in past
All previous Oracle commercial features now in OpenJDK.
java product management blog good source for minor differences between Oracle and OpenJDK
jdk.java.net for openjdk binaries
New release means late binding of features (old releases very ‘waterfall’ type releases). In new release late freeze date very close to GA date.
180 EA builds of j9, 45 EA builds in j10, 27 EA builds in j11
Still same speed of dev but split across more releases.
J12 has 4 JEPS so far
New tools to manage change.
jdeps in J8 to show class dependencies
If you use libraries you inherit any mistakes, uses of unsafe, etc
in j9, jpedrscan shows deprecated api elements -for-removal flag limits to ones which will be removed
Incubator modules for non-final apis to get feedback from j9
Features can be seen in OpenJDK projects and will appear when ready
Portola – containers.
Valhalla – performance/memory
Panama – better JNI
Loom – fibers for threading
Amber – lang improvements 9dynamic class-file constants, raw string literals,switch statements
Project Skara – move to git

My takeaways – If you want to see where Java is heading check out the projects. The new tools make updating much easier

Benefiting from Java 9 Improvements [DEV5372] 2005

Full room for Venkat
improvements/changes/additions
Not covering modules as covered elsewhere
interface now have private methods (can already have default and static). Cannot have private default. Should b used sparingly
final in try with resources (finalise now deprecated in Java9. can implement AutoCloseable – added in J7 – in your code)
In life and programming we seem to solve one se too programming only to create a new set of problems
_ is internal symbol for “I don’t care” – used in Scala and Kotlin
In j8 _ a warning and now error so can be used in later release for something.
Stream – Java8 has limit and skip on stream but based on stream not valid values if you filter.Added takeWhile (like a break) and dropWhile (like Haskell).
IntStream iterate makes it easy to replace for loops with increments other than 1 IntStream.iterate(0, i ->i <=15, i -> i + 3)
Optional. Allows you to avoid null. Do not use as parameter for method. Optional unfortunately has get method which will throw error if no value. So avoid. use result.orElse(default) – in java11 orElseThrow(). Java 9 adds ifPresentOrElse() .ifFirst can take stream

My takeaways – While jigsaw is exciting, there is lots of other cool stuff in Java9

JDK 9, 10, and 11: Pitfalls for the Unwary

Show of hands – virtually all audience on j8
If on 8 now, move to 11 not 9 or 10
Compatibility very important
minor issues 1.4 to 5 – assert became keyword and enum now reserved
Deprecation added in 1.1
In j8 492 deprecated API elements, none removed so far
J9 start long overdue cleanup to remove stuff
Clean code should work
in j9 big change module system
75 modules in OpenjdK (27 javase and 48 jdk). 14 additional in Oracle (8 javaFX, 2 oracle specific)
Most internal APIs now encapsulated (sun.misc.Unsafe) – used in common libraries so you may be using them.
You can ignore modulesystem
Module jar to module path – becomes automatic module
upgrade code to proper module
You can use –illegal-access permit|warn|debug\deny (big kill switch) to allow old style access and turn off encapsulation. Also –add-exports/–add-opens for more granular control. Add-exports can be added in jar manifest
jdeps
java.se.ee module not included by default in j9/10 (reactivation, corba, xml)
accessed via –add-modules All have standalone on Maven central. Can deploy on module or classpath
_ is now a keyword (but __ okay for var name)
Deleted 6 methods in j9 (mainly as issue with these in modularisation)
new version strings now semantic versioning ie 1.8.0_131
JNLP now strict parsing on config file
ext directory now removed
lots of GC options removed
Logging changed in JVM (previously each had own)
Lots of JVM flags removed
50 command flags no longer work and will stop JVM from starting if used

My takeaways – Documented key changes and ways to ease transition

Migrating Java UI Client Applications to OpenJDK 11 [DEV5990]

Most desktop apps using J8. Recommended migration to j11
Plugin, webstart, javafX not part of OpenJDK
J7 first simultaneous release of OpenJDK and Oracle JDK
most users still downloaded commercial releases and little OpenJDK testing as result
Now converging means changes needed.
Font rasterisation T2K >freetype
lucida fonts removed in j11
Anti-alias Ductus -> marlin
JPEG classes gone (com.sun.jpeg.codec). Still java.imageio
image processing Kodak >little cms. losing profiles for common colourspaces and replaced with Open source. But will give different results
hiDpi support in windows. now scaled up to match. May need apps tweaking (ie Icon images scaled up)
no javafX in j11 – needs downloading and adding
Deployment technologies removed – plugin, webstart, appletviewer. Now need to be an application
Plan to have packager in j12 to create bundles to run

My takeaways – lots of changes under the hood. Will need some planning to ensure not issue.

JUnit 5: The Next Step in Automated Testing for Java [DEV5916]

Why change? (JUnit 4 released 2006)
Goals;-
Modernise (use J8)
Modularise
Extensible
backwards compatible
3 major modules:-
vintage (backward compatibility)
Platform (test launch and tooling)
Jupiter (new cool stuff)
Demo to show backwards compatibility.
JUnit5 replaces rules with extension model. @RuleMigrationSupport annotation needed in J5 if you still use
assertAll make sit easy to run all tests
@DisplayName and Emoji support
Some language changes to clarify usage
Extendwith Extension API
Dependency Injection (ie for a mock)
TestInfo object available
@ValueSource allows easy definition
Repeated tests
Dynamic tests
Test interfaces
tests can be disables via OS, jdk version, custom logic
parallel test execution
Nested tests
Assumptions
ConsoleLauncher
@billykorando

My takeaways – Great backwards compatibility but worth updating the tests to use new features

The Seven Deadly Sins of Software Development [DEV6081] [DEV5916]

1. No tests. Legacy code is code with no tests. Avoid the copy/paste design pattern
2. god objects. One huge class
3. comments. Delete commented out code. Comments should be safe,legal and rare.
4. dead code. kill it.
5. Driving without a seat belt. Antiviruses, locking down windows (shutup10), sandbox your browser, vpn and browsers
6. Not knowing tool you use. Learn to type as keyboard main input device. and have a decent keyboard. Then use keyboard shortcuts
7. bad names. being lazy.
keepcalmandrefactor.com

My takeaways – great fun session to finish the show!