Codenameone并发或同步访问数据结构

Question

I noticed that the java.util.concurrent package is not included as part of CN1 subset of Java. On the other hand, I noticed that the CN1 lib includes ConcurrentModificationException located in java.util package.

1. Why is the concurrent package not included ? Are there any technical reasons I am not aware of?
2. How can I guarantee that I don't run into hard-to-debug concurrency issues?

Answer 1

The concurrency package was added late to Java and the language supported concurrent access well before that through the synchronized keyword and other language level semantics.

ConcurrentModificationException has nothing to do with the concurrent package as it relates to the collections API. There are many strategies to dealing with concurrent access to shared resources and this all depends on the case you are dealing with but here are a couple of important distinctions:

• Creating threads on the device is bad. You don't have many cores at your disposal and even if you run in a separate thread it will impact UI performance so you should minimize thread creation for performance. Codename One takes this strategy internally by doing almost everything on the EDT hence avoiding the overhead of thread synchronization and sanitizing the native thread access for portability https://www.codenameone.com/manual/edt.html

• We do networking on network threads but provide builtin API's & callbacks that go back into the EDT. That mechanism is also exposed by the simplified Easy Thread class