Repeat the previous exercise using Java Lock variables.

Data from Repeat the previous exercise 

Give amore efficient solution to the previous exercise that avoids the use of notify All. (Warning: It is tempting to observe that the buffer can never be both full and empty at the same time, and to assume therefore that waiting threads are either all producers or all consumers. This need not be the case, however: if the buffer ever becomes even a temporary performance bottleneck, there may be an arbitrary number of waiting threads, including both producers and consumers.)