Crystal Sheldon
@crystal-l-sheldon.bsky.social
Supporter of Computer Science Education with a focus on Java.
Check out free Java resources here: Learn.java
My posts are my own.
Check out free Java resources here: Learn.java
My posts are my own.
🎥 Need quick, effective tutorial videos for your students? We’re regularly adding new bite-sized lessons! Find them in our current playlist (permanent channel coming soon). Have a topic request? Let me know—your feedback drives our content!
#learnjava #teachjava
www.youtube.com/playlist?app...
#learnjava #teachjava
www.youtube.com/playlist?app...
Learn.java
Learn.java provides learning tutorials for beginners, students, and teachers of Java. Check https://learn.java
www.youtube.com
January 30, 2026 at 12:05 PM
🎥 Need quick, effective tutorial videos for your students? We’re regularly adding new bite-sized lessons! Find them in our current playlist (permanent channel coming soon). Have a topic request? Let me know—your feedback drives our content!
#learnjava #teachjava
www.youtube.com/playlist?app...
#learnjava #teachjava
www.youtube.com/playlist?app...
Snowed in? Iced in? Learn a new skill at Learn.java!
Learn.java: The Destination for Java Beginners, Students, and Teachers
Learn.java
January 26, 2026 at 1:47 PM
Snowed in? Iced in? Learn a new skill at Learn.java!
What's new on Learn.java this week?
- We've added two new FRQs (one was late last week):
- FRQ 4 2D arrays - Game Board: lnkd.in/dQDMM9Ff
- FRQ 3 ArrayList - Efficient Workout: lnkd.in/exgfv9QH
- We've added two new FRQs (one was late last week):
- FRQ 4 2D arrays - Game Board: lnkd.in/dQDMM9Ff
- FRQ 3 ArrayList - Efficient Workout: lnkd.in/exgfv9QH
Learn.java: The Destination for Java Beginners, Students, and Teachers
Learn.java
January 23, 2026 at 2:13 PM
What's new on Learn.java this week?
- We've added two new FRQs (one was late last week):
- FRQ 4 2D arrays - Game Board: lnkd.in/dQDMM9Ff
- FRQ 3 ArrayList - Efficient Workout: lnkd.in/exgfv9QH
- We've added two new FRQs (one was late last week):
- FRQ 4 2D arrays - Game Board: lnkd.in/dQDMM9Ff
- FRQ 3 ArrayList - Efficient Workout: lnkd.in/exgfv9QH
Just posted a new #APCSA FRQ for practicing question type 3: Data and ArrayList. Check it out here: learn.java/learning/les...
AP Computer Science A Free Response Practice - Data Analysis and ArrayList - Workout Time - Learn.java
Practice writing code to complete a free response question 3 to analyze workout data in an ArrayList
learn.java
January 21, 2026 at 1:11 PM
Just posted a new #APCSA FRQ for practicing question type 3: Data and ArrayList. Check it out here: learn.java/learning/les...
I've added another practice AP CSA FRQ 4 to Learn.java. Have you students complete and run their code right in the browser.
learn.java/learning/les...
learn.java/learning/les...
Learn.java: The Destination for Java Beginners, Students, and Teachers
Learn.java
January 12, 2026 at 3:13 PM
I've added another practice AP CSA FRQ 4 to Learn.java. Have you students complete and run their code right in the browser.
learn.java/learning/les...
learn.java/learning/les...
What's NEW this week on Learn.java?
- Added some tutorial videos to the array and 2D array pages
- Added a new AP CSA FRQ 4 on 2D Array (learn.java/teachers/apc...)
- Added some tutorial videos to the array and 2D array pages
- Added a new AP CSA FRQ 4 on 2D Array (learn.java/teachers/apc...)
Learn.java: The Destination for Java Beginners, Students, and Teachers
Learn.java
December 18, 2025 at 9:04 PM
What's NEW this week on Learn.java?
- Added some tutorial videos to the array and 2D array pages
- Added a new AP CSA FRQ 4 on 2D Array (learn.java/teachers/apc...)
- Added some tutorial videos to the array and 2D array pages
- Added a new AP CSA FRQ 4 on 2D Array (learn.java/teachers/apc...)
Reposted by Crystal Sheldon
We've embedded the Java Playground into tutorials and practice! Check it out: https://social.ora.cl/6013AkVSD
October 10, 2025 at 3:01 PM
We've embedded the Java Playground into tutorials and practice! Check it out: https://social.ora.cl/6013AkVSD
Reposted by Crystal Sheldon
Hear from Tammy Pirmann, professor from Drexel University, on how she uses students' interests to drive engagement and help students uncover the power of computer science. https://social.ora.cl/6018fWimM
October 22, 2025 at 3:00 PM
Hear from Tammy Pirmann, professor from Drexel University, on how she uses students' interests to drive engagement and help students uncover the power of computer science. https://social.ora.cl/6018fWimM
Reposted by Crystal Sheldon
Learn how to use pattern matching with records and switch case patterns to write program code that is more readable. https://social.ora.cl/6019AD9mT
October 27, 2025 at 3:01 PM
Learn how to use pattern matching with records and switch case patterns to write program code that is more readable. https://social.ora.cl/6019AD9mT
A new #APCSA Free Response question for FRQ 4: 2D array has been posted. Check it out: learn.java/learning/les...
AP Computer Science A Free Response Practice - 2D Array - Mutual Connections - Learn.java
Practice writing code to complete a free response question 4 to analyze data in a 2D Array
learn.java
December 17, 2025 at 6:12 PM
A new #APCSA Free Response question for FRQ 4: 2D array has been posted. Check it out: learn.java/learning/les...
Lots of teachers get the "what is it like to be a software engineer" question. Jim has many podcasts on Duke's Corner where you can hear from professionals about the work that they do. Loved meeting Chris. He has a great story! Give it a listen!
Duke's Corner Podcast with Chris Hermansen, a data analyst, developer, and consultant on the technical features in Java, developer creativity, career advice for students, and the use of Java in real world applications such as forestry. #java dukescorner.libsyn.com/site/chris-h...
Duke's Corner: Chris Hermansen: Don't be Afraid to Create
Chris Hermansen: Don't be Afraid to Create Summary Jim Grisanzio from Java Developer Relations talks with Chris Hermansen, a Java developer, consultant, and data analyst from Canada. Chris discovered ...
dukescorner.libsyn.com
December 17, 2025 at 3:09 PM
Lots of teachers get the "what is it like to be a software engineer" question. Jim has many podcasts on Duke's Corner where you can hear from professionals about the work that they do. Loved meeting Chris. He has a great story! Give it a listen!
Just added some video tutorials to our 2D array pages. Tracing through code can help to make meaning of the syntax and make it more concrete.
- Introduction to Two-Dimensional Arrays: lnkd.in/eHx9KmnR
- Iterating Over Two-Dimensional Arrays: lnkd.in/eFf95Kq6
- Introduction to Two-Dimensional Arrays: lnkd.in/eHx9KmnR
- Iterating Over Two-Dimensional Arrays: lnkd.in/eFf95Kq6
LinkedIn
This link will take you to a page that’s not on LinkedIn
lnkd.in
December 16, 2025 at 7:59 PM
Just added some video tutorials to our 2D array pages. Tracing through code can help to make meaning of the syntax and make it more concrete.
- Introduction to Two-Dimensional Arrays: lnkd.in/eHx9KmnR
- Iterating Over Two-Dimensional Arrays: lnkd.in/eFf95Kq6
- Introduction to Two-Dimensional Arrays: lnkd.in/eHx9KmnR
- Iterating Over Two-Dimensional Arrays: lnkd.in/eFf95Kq6
Just added some video tutorials to our Array Learn pages. Tracing through code can help to make meaning of the syntax and make it more concrete.
- Introduction to Arrays: learn.java/learning/tut...
- Iterating Over Arrays: learn.java/learning/tut...
- Introduction to Arrays: learn.java/learning/tut...
- Iterating Over Arrays: learn.java/learning/tut...
Introduction to Arrays an AP Computer Science A Topic - Learn.java
Learn how to create an array to store data
learn.java
December 16, 2025 at 1:39 PM
Just added some video tutorials to our Array Learn pages. Tracing through code can help to make meaning of the syntax and make it more concrete.
- Introduction to Arrays: learn.java/learning/tut...
- Iterating Over Arrays: learn.java/learning/tut...
- Introduction to Arrays: learn.java/learning/tut...
- Iterating Over Arrays: learn.java/learning/tut...
What's new on Learn.java this week?
- array practice
- array tutorial images to illustrate what it looks like
- String split method practice
- 2D array tutorial
- December newsletter
- Recording of J Card Visuals with Text Blocks
- array practice
- array tutorial images to illustrate what it looks like
- String split method practice
- 2D array tutorial
- December newsletter
- Recording of J Card Visuals with Text Blocks
Learn.java: The Destination for Java Beginners, Students, and Teachers
Learn.java
December 12, 2025 at 4:27 PM
What's new on Learn.java this week?
- array practice
- array tutorial images to illustrate what it looks like
- String split method practice
- 2D array tutorial
- December newsletter
- Recording of J Card Visuals with Text Blocks
- array practice
- array tutorial images to illustrate what it looks like
- String split method practice
- 2D array tutorial
- December newsletter
- Recording of J Card Visuals with Text Blocks
Advent of Code Day 6 part 1 - My solution might be ugly...
- Used a record to do the "Math" learn.java/learning/tut...
- Added a method to clean my data and remove the spaces. Certain there's an easier way, but then you couldn't talk about clean data!
github.com/clfurman/Adv...
- Used a record to do the "Math" learn.java/learning/tut...
- Added a method to clean my data and remove the spaces. Certain there's an easier way, but then you couldn't talk about clean data!
github.com/clfurman/Adv...
Creating and Using Records - Learn.java
Creating and using records
learn.java
December 10, 2025 at 6:15 PM
Advent of Code Day 6 part 1 - My solution might be ugly...
- Used a record to do the "Math" learn.java/learning/tut...
- Added a method to clean my data and remove the spaces. Certain there's an easier way, but then you couldn't talk about clean data!
github.com/clfurman/Adv...
- Used a record to do the "Math" learn.java/learning/tut...
- Added a method to clean my data and remove the spaces. Certain there's an easier way, but then you couldn't talk about clean data!
github.com/clfurman/Adv...
To support you completing the Advent of Code, here are some 2D array tutorials.
- Intro to 2D Arrays: learn.java/learning/tut...
- Iterating Over 2D Arrays: learn.java/learning/tut...
Practice sets to come! Enjoy!
- Intro to 2D Arrays: learn.java/learning/tut...
- Iterating Over 2D Arrays: learn.java/learning/tut...
Practice sets to come! Enjoy!
Introduction to Two-Dimensional Arrays - Learn.java
Learn how to create two-dimensional arrays to store data
learn.java
December 10, 2025 at 6:02 PM
To support you completing the Advent of Code, here are some 2D array tutorials.
- Intro to 2D Arrays: learn.java/learning/tut...
- Iterating Over 2D Arrays: learn.java/learning/tut...
Practice sets to come! Enjoy!
- Intro to 2D Arrays: learn.java/learning/tut...
- Iterating Over 2D Arrays: learn.java/learning/tut...
Practice sets to come! Enjoy!
Reposted by Crystal Sheldon
A bunch of resources for beginners and also not so much beginners, I gladly recommend! 👏👏👏
What's new on Learn.java this week? Motivated by doing Advent of Code and looking for ways to support solutions, I've added the following tutorials this week.
- Reading from a text file
- Intro to Arrays
- Iterating over Arrays
- Using Split on Arrays
- Reading from a text file
- Intro to Arrays
- Iterating over Arrays
- Using Split on Arrays
Learn.java: The Destination for Java Beginners, Students, and Teachers
Learn.java
December 6, 2025 at 8:27 AM
A bunch of resources for beginners and also not so much beginners, I gladly recommend! 👏👏👏
What's new on Learn.java this week? Motivated by doing Advent of Code and looking for ways to support solutions, I've added the following tutorials this week.
- Reading from a text file
- Intro to Arrays
- Iterating over Arrays
- Using Split on Arrays
- Reading from a text file
- Intro to Arrays
- Iterating over Arrays
- Using Split on Arrays
Learn.java: The Destination for Java Beginners, Students, and Teachers
Learn.java
December 5, 2025 at 5:33 PM
What's new on Learn.java this week? Motivated by doing Advent of Code and looking for ways to support solutions, I've added the following tutorials this week.
- Reading from a text file
- Intro to Arrays
- Iterating over Arrays
- Using Split on Arrays
- Reading from a text file
- Intro to Arrays
- Iterating over Arrays
- Using Split on Arrays
Advent of Code Day 2...
Seemed really easy, until bullet 3! LOL.
- Added a record to return endSpot and a zeroCount
- Modified my easy mod solution to use a while loop.
- Realized I was double counting if I went negative but also started at zero.
github.com/clfurman/Adv...
Seemed really easy, until bullet 3! LOL.
- Added a record to return endSpot and a zeroCount
- Modified my easy mod solution to use a while loop.
- Realized I was double counting if I went negative but also started at zero.
github.com/clfurman/Adv...
GitHub - clfurman/Advent-of-Code-2025: Java solutions for the advent of code.
Java solutions for the advent of code. . Contribute to clfurman/Advent-of-Code-2025 development by creating an account on GitHub.
github.com
December 3, 2025 at 9:05 PM
Advent of Code Day 2...
Seemed really easy, until bullet 3! LOL.
- Added a record to return endSpot and a zeroCount
- Modified my easy mod solution to use a while loop.
- Realized I was double counting if I went negative but also started at zero.
github.com/clfurman/Adv...
Seemed really easy, until bullet 3! LOL.
- Added a record to return endSpot and a zeroCount
- Modified my easy mod solution to use a while loop.
- Realized I was double counting if I went negative but also started at zero.
github.com/clfurman/Adv...
Reading data from a file in a new topic in the #APCSA. Don't wait until ArrayLists to start File reading, students only need to understand method calling and while loops!
Check out the tutorial here: learn.java/learning/tut...
Then try Day 1 of the Advent of Code!
Check out the tutorial here: learn.java/learning/tut...
Then try Day 1 of the Advent of Code!
Reading from a Text File using File and Scanner - Learn.java
Reading data from a text file using the File and Scanner classes.
learn.java
December 2, 2025 at 8:12 PM
Reading data from a file in a new topic in the #APCSA. Don't wait until ArrayLists to start File reading, students only need to understand method calling and while loops!
Check out the tutorial here: learn.java/learning/tut...
Then try Day 1 of the Advent of Code!
Check out the tutorial here: learn.java/learning/tut...
Then try Day 1 of the Advent of Code!
Advent of Code - Did you get a Day 1 Star?
- file reading in the AP CSA style (for better or worse).
- records to capture the rotation as a String and a number!
- void main() and IO class
- Please don't judge how I dealt with the negative numbers :)
github.com/clfurman/Adv...
- file reading in the AP CSA style (for better or worse).
- records to capture the rotation as a String and a number!
- void main() and IO class
- Please don't judge how I dealt with the negative numbers :)
github.com/clfurman/Adv...
GitHub - clfurman/Advent-of-Code-2025: Java solutions for the advent of code.
Java solutions for the advent of code. . Contribute to clfurman/Advent-of-Code-2025 development by creating an account on GitHub.
github.com
December 2, 2025 at 6:47 PM
Advent of Code - Did you get a Day 1 Star?
- file reading in the AP CSA style (for better or worse).
- records to capture the rotation as a String and a number!
- void main() and IO class
- Please don't judge how I dealt with the negative numbers :)
github.com/clfurman/Adv...
- file reading in the AP CSA style (for better or worse).
- records to capture the rotation as a String and a number!
- void main() and IO class
- Please don't judge how I dealt with the negative numbers :)
github.com/clfurman/Adv...
The recording of the Java Card Game Challenge: Shuffle the Deck webinar has been posted. Check it out here: youtu.be/catdtD1fyvw
Our final webinar of this series on Card Visuals with Text Blocks is this Wed Dec 3 at 3pm.
Register here: oracle.zoom.us/webinar/regi...
Our final webinar of this series on Card Visuals with Text Blocks is this Wed Dec 3 at 3pm.
Register here: oracle.zoom.us/webinar/regi...
Java Card Game Challenge 5: Shuffling the Deck
YouTube video by Java
youtu.be
December 1, 2025 at 7:12 PM
The recording of the Java Card Game Challenge: Shuffle the Deck webinar has been posted. Check it out here: youtu.be/catdtD1fyvw
Our final webinar of this series on Card Visuals with Text Blocks is this Wed Dec 3 at 3pm.
Register here: oracle.zoom.us/webinar/regi...
Our final webinar of this series on Card Visuals with Text Blocks is this Wed Dec 3 at 3pm.
Register here: oracle.zoom.us/webinar/regi...
This short week on Learn.java!!!
Some new Practice for Nested Loops:
- Evaluating nested loops
- Writing nested loops
Some new videos have been added to these Learn pages:
- Intro to determine a data type
- Naming variables
- Declaring and initializing variables
Some new Practice for Nested Loops:
- Evaluating nested loops
- Writing nested loops
Some new videos have been added to these Learn pages:
- Intro to determine a data type
- Naming variables
- Declaring and initializing variables
November 25, 2025 at 2:33 PM
This short week on Learn.java!!!
Some new Practice for Nested Loops:
- Evaluating nested loops
- Writing nested loops
Some new videos have been added to these Learn pages:
- Intro to determine a data type
- Naming variables
- Declaring and initializing variables
Some new Practice for Nested Loops:
- Evaluating nested loops
- Writing nested loops
Some new videos have been added to these Learn pages:
- Intro to determine a data type
- Naming variables
- Declaring and initializing variables
Java Card Game Challenge #6 - Create visuals for your cards using text blocks. You could also get creative and do this using Java FX.
Come learn all about how to format output with text blocks.
When: Wednesday, December 3rd, at 3pm ET
Register: lnkd.in/ehn_5czq
Come learn all about how to format output with text blocks.
When: Wednesday, December 3rd, at 3pm ET
Register: lnkd.in/ehn_5czq
November 21, 2025 at 2:23 PM
Java Card Game Challenge #6 - Create visuals for your cards using text blocks. You could also get creative and do this using Java FX.
Come learn all about how to format output with text blocks.
When: Wednesday, December 3rd, at 3pm ET
Register: lnkd.in/ehn_5czq
Come learn all about how to format output with text blocks.
When: Wednesday, December 3rd, at 3pm ET
Register: lnkd.in/ehn_5czq
What's new this week on Learn.java?
- An #APCSA free response practice question for data analysis and ArrayList: learn.java/learning/les...
- The last of our Java Card Game Challenges has been posted. Register for our webinar on Dec 3 at 3pm ET: learn.java/teachers/tea...
- An #APCSA free response practice question for data analysis and ArrayList: learn.java/learning/les...
- The last of our Java Card Game Challenges has been posted. Register for our webinar on Dec 3 at 3pm ET: learn.java/teachers/tea...
Learn.java: The Destination for Java Beginners, Students, and Teachers
Learn.java
November 21, 2025 at 12:10 PM
What's new this week on Learn.java?
- An #APCSA free response practice question for data analysis and ArrayList: learn.java/learning/les...
- The last of our Java Card Game Challenges has been posted. Register for our webinar on Dec 3 at 3pm ET: learn.java/teachers/tea...
- An #APCSA free response practice question for data analysis and ArrayList: learn.java/learning/les...
- The last of our Java Card Game Challenges has been posted. Register for our webinar on Dec 3 at 3pm ET: learn.java/teachers/tea...