API methods and synchronization

[Mike Hays]

I call Random.nextLong() and HashMap.toString() from code that is accessed by multiple threads. Should calls to these methods be synchronized? I believe Random is threadsafe. I know that HashMap is not, but I'm not sure about toString().

This question may be better suited to the Threads forum, but since the issue came up while working on the SCJD exam I'll post it here.

[K. Tsang]

Howdy Mike. I don't know why you need to use the Random class when the record numbers are calculated from the Sun data file. The toString() method in HashMap isn't synchronized.

[Mike Hays]

Howdy,

I use the Random class' nextLong() method to generate lock cookies.

Since toString() is not synchronized does that mean I need something like

        masterLock.lock();

        try {
            return lockedRecords.toString();
        } finally {
            masterLock.unlock();
        }

where masterLock is used to protect lockedRecords?