Trying to synchronize method within runnable

Question

I have a ConcurrentMap that gets instantiated outside of my runnables, but shared and updated within / accross the runnables. My runnables need to be concurrent, but my conc

Answer 1

You should avoid synchronizing when using a ConcurrentMap. It provides other methods for handling these types of operations. For this case the putIfAbsent method should be preferred over a contains and then a put.

public void runAnalysis(int index) {
    if (concurrentMap.putIfAbsent(index, "thread " + thread) == null) {
        System.out.println("put " + index + " thread " + thread);
    } else {
        System.out.println("contains integer " + index);
    }
}