- Write pre and postcondition statements for the methods specified in the Lock interface (shown below):

public interface Lock {

public boolean locked();

public void unlock(String key);

public void setKey(int code, String newKey); }

- Write a class that implements the Lock interface. Your class should include a set of instance variables, a set of constructors, and must implement the methods specified in the interface. You must also include a simple main method to demonstrate each of your methods in action.

instance variables: ____________________________________________________

constructor(s): _______________________________________________________

locked: _____________________________________________________________

unlock: _____________________________________________________________

setKey: ______________________________________________________________