Lecture 19

Lecture 19: Thread Safety; Java Packages
Date: Friday, April 22, 2022

Agenda

Announcements
- Final Project
  - 2 weeks to go
  - keep making progress, let me know if I can help
  - look ahead to upcoming class examples for things like collision detection
  - project demos will be part of the Academic Showcase, and we are scheduled for 10-11 AM, Friday, May 6, RB 340
- Lab 10: Threads for Parallel Processing (in Canvas and GitHub)
  - if your group did not get up through the end of Part 2, try to get through that before your next lab
  - otherwise feel free to ignore until your next lab, there will be no new lab next week
- Reminders about CSIS-301 and CSIS-330 for Fall 2022
Exam 2 thoughts and improvement opportunities
Thread safety
- a data structure example of a race condition
- intrinsic locking with synchronized methods
- explicit locks to enforce mutual exclution in critical sections
In-class exercise (3 points), create a document in your CSIS 225 shared Google drive folder, submit a link to it in Canvas as In-Class 19
From the current topic notes:

We have a list with one element:
```
  SimpleLinkedList<Integer> x = new SimpleLinkedList<Integer>();
  x.add(1);
```
Then two threads each try to remove a value to make use of it in some way:
```
  if (!x.isEmpty()) {
    int val = x.get(0);
    x.remove(0);
    // do something 
  }
```
What is the intended behavior here? What could go wrong?
Java Packages
- Java API packages and modules
- using packages
- A class conflict from wildcard imports

Terminology

Examples