You might have a piggy bank or some other receptacle to hold your spare coins. The piggy bank holds the coins but gives them no other organization. And certainly the bank can contain duplicate coins....

You might have a piggy bank or some other receptacle to hold your spare coins. The piggy bank holds the coins but gives them no other organization. And certainly the bank can contain duplicate coins. A piggy bank is like a bag, but it is simpler, as it has only three operations: You can add a coin to the bank, remove one (you shake the bank, so you have no control over what coin falls out), or see whether the bank is empty. Design a class PiggyBank, assuming that you have the class Coin. Specify each method of PiggyBank by stating the method’s purpose; by describing its parameters; and by writing preconditions, post-conditions, and a pseudocode version of its header. Then write a Java interface for these methods that includes javadoc-style comments.