What's the difference between lock and synchronization? Lock allows for fine control in a method, synchronize is for the whole method. Synchronize works with conditions for multiple levels of thread control, and lock is for coarse thread control. This is a trick question and the differences are too enormous to summarize easily. Synchronize forces threads to run in parallel, lock allows one-at-a-time operation. It is important to change an object after it has been already instantiated. How is this done? With inheritance. O With a Wrapper implementation. With a Mutator implementation. It is not done. What is a FlowLayout good for? O Neatly organizing Ul items in an even arrangement. Having Ul items be resized to fit the area available. Changing Ul items so they can be shown differently. Displaying a series of irregular Ul items in sequence. What's the difference between implementing Runnable and extending Thread? Runnable is for JavaFX, Thread is for Swing. Too many to mention because they do two entirely different things. Not much, really. Reentrant locks only work on Threads and not Runnables.