(4 pts)R15.3One way of implementing a calendar is as a map from date objects to event objects. However, that only works if there is a single event for a given date. How can you use another collection type to allow for multiple events on a given date?

(4 pts) R15.8Explain what the following code prints. Draw a picture of the linked list and the iterator position after each step. LinkedList staff = new LinkedList( ); ListIterator iterator = staff.listIterator( ); iterator.add( "Tom" ); iterator.add( "Diana" ); iterator.add( "Harry" ); iterator = staff.listIterator( ); if ( iterator.next( ).equals( "Tom" ) ) { iterator.remove( ); } while ( iterator.hasNext( ) ) { System.out.println( iterator.next( ) ); }

(2 pts)R15.16Suppose the strings "A" ... "Z" are pushed onto a stack. Then they are popped off the stack and pushed onto a second stack. Finally they are all popped off the second stack and printed. In which order are the strings printed?

(2 pts)R15.18A map can be implemented as a set of (key, value) pairs. Explain.

(8 pts) E15.9Your task is to break a number into its individual digits, for example, to turn 1729 into 1, 7, 2, and 9. It is easy to get the last digit of a numbernasn% 10. But that gets the numbers in reverse order. Solve this problem with a stack. Your program should ask the user for an integer, then print its digits separated by spaces.