The idea is to avoid the costly synchronization for all invocations of the method except the first.

这个想法是为了避免对除第一次调用外的所有调用都实行同步的昂贵代价。

youdao

However, because the method is synchronized, you pay the cost of synchronization for every invocation of the method, even though it is only required on the first invocation.

尽管如此，由于该方法是synchronized的，需要为该方法的每一次调用付出同步的代价，即使只有第一次调用需要同步。

youdao

The real value here is that the getWhatImReading method is executed without synchronization of any kind, whereas the setWhatImReading is executed as an atomic operation.

这里真正的价值在于，getWhatImReading 方法未经任何形式的同步便被执行，而 setWhatImReading 是作为一个原子操作执行的。

youdao