Tag Archives: java

Announcing our new OCP Java 21 1Z0-830 Exam Study Guide!

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OCP 21 Announcement

Jeanne and I thrilled to announce our new Java OCP 21 Study Guide is coming out soon! This is based on the recently announced Oracle 1Z0-830 Exam for Java 21. Preorders starting now!

You can be confident when purchasing our book that it contains everything you need to pass the exam. In fact, we were part of a select group that worked with Oracle to help develop and refine the exam. We even helped kick JDBC off the exam (as it only tested obscure topics), so you have one less thing to study!

What’s new about the 1Z0-830 Java 21 exam? Obviously new features of Java 21 like virtual threads, sequenced collections, and much broader support for pattern matching are covered. What’s the same? The format (50 questions), time (90 minutes), and passing score (68%) are the same as the previous exam.

Jeanne and I are nearly done writing the book so expect this in book stores by the end of the year! We’ll continue to post updates on the OCP 21 Book page.

[dev nexus 2024] teaching your kid programming from the perspective of a kid

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Speaker: Cassandra Chin

@cassandraonjava

For more, see the 2024 DevNexus Blog Table of Contents

General

  • Steven Chin’s daughter.
  • Worked with coding and YAML in MInecraft
  • Starting teaching kids to program at 14 at conferences
  • Junior in college
  • Creating podcast at internship for younger people (ex college)

Tech diversity

  • 20 years of feale tech panels and still need
  • Women who try AP Comp Sci in high school ten times more like to major it.
  • Black/Latino students seven times more lilkely.
  • Need to provide opportunity
  • Even at 6 year old, kids think computers are more suited to boys. Fifth grade it tapers down so sweet spot for starting.

Kids and code

  • Schools mandate human/world languages, but not coding languages
  • Since schools dont always provide, parents need to
  • Not all screen time is equal
  • Limit youtube
  • Minecraft in middle
  • Best use is learning to code – ex: Scratch
  • Redirect computer use vs taking away

Mistakes for parents to avoid

  • Don’t leave your daughters out. Bring to tech event
  • Computers at home matter – an actual computer, not a tablet. Lets do more than play mobile games
  • Don’t need to be good at math. While Assembly requires math, nobody uses anymore Modern programs use logic, not math
  • Kids dislike math the most followed by foreight language. Computers is third highest. Both things above are types of art.
  • Don’t start with books like Discrete Math
  • Give examples of programmers that they can relate to
  • Don’t start with boring parts like what an array is. Better to start with legos
  • Don’t do the code for the kids. They won’t learn. Never grab mouse or keyboard. Means content too har

Geniuses

  • Anyone can learn to code. Don’t have to be super smart.
  • Kids told programmers are genious do worse than kids who think practies will make them better

Books

  • Phippys AI Friend – comes with online workshop that takes about an hour. Actually use boo as prop
  • Coding for Kids Python
  • GIrls who Code

Helping kids

  • Relate to your kids hobbies. Ex: discuss who built
  • Lego Spike – build robot and do block coding
  • Mbot (Make Block). Uses screws instead of legos. Don’t have to use blocks
  • Hour of Code. Lots of themes
  • Choose age appropriate. Often we choose twoo hard
  • Squishy circuits for 3-9 year olds
  • Raspberry Pi and Arduino – 9-15 years old
  • Groups of two works best. When three kids, the younest will often feel left out
  • Take kids to localy run workshops – ex: confernces, girls who code

My take

I like her responses to Todd’s mini interview a the begining while they dealt with AV issues. Great humor. I liked that she made a joke about her dad being there to tell jokes. I also like “I’m not the daughter of Steven Chin; I have a name”. Great content throughout hether new to the topic or not.

The content resonated well. I gave my best friends five year old (daughter) a toy robot for her fifth birthday. I enjoyed seeing her play. I now have a gift idea for next year!

I also liked the demo from her book!

[dev nexus 2024] a glance at the java performance toolbox

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Speaker: Ana Maria Mihalceanu

@ammbra1508

For more, see the 2024 DevNexus Blog Table of Contents

What is performance

  • From user POV, how much work can do in a reasonable amount of time
  • From business, what is cost in computational resources needed to provide that user experience

Cloud

  • Practically unlmited resources
  • Reasonable cost

Container images

  • Tools to build container images – docker, jib, kaniko, buidah, etc
  • All started with a Dockerfile
  • Other tools arrived later to make easier

JLink

  • JRE stopped being included in Java 11
  • Can use jlink to include custom JRE with just modules need.
  • Can also omit man pages and header files.
  • Compress zip-9 offers the best compression.

Fine Tuning JVM Flags

  • Ergonomics docs – process for JVM/GC to tune performance measures
  • Tune min/max heap size with -Xms and -Xmx
  • Consider Java heap ratio

jcmd

  • Tracks native memory
  • Want available in container
  • Add jdk.jcmd module to application

Other commands/tools

  • Use jinfo to see what flags used in app
  • Helps when don’t know all flag names
  • Look for amount of memory reserved and amount used
  • Look for big values
  • JConsole – can see graph of memory use
  • jstat – garbage collection statistics
  • jmap – histogram of heap summary
  • Profiling with Java Flight Recorder – use when looking for something, not all the time. Need jdk.jfr module. Can specify how long to record.
  • Prometheus server – monitors/alerts on events
  • JFR Streaming – sends metrics to monitoring service

Sample app for testing at https://github.com/ammbra/performance-glance

My take

Good information and good demo. It was nice seeing the commands actually get used. Clear how to apply.