[ Team LiB ] Page 634
[ Team LiB ] 11 Collections and Maps 11.1 (a), (d), and (e) Set, Collection and Map are core interfaces in the collections framework. LinkedList is a class that implements the List interface. There is no class or interface named Bag. 11.2 (b) and (e) The java.util package provides map implementations named HashMap and TreeMap. It does not provide any implementations named HashList, ArraySet, and ArrayMap. 11.3 (d) The List interface is implemented by collections that maintain sequences of possibly non-unique elements. Elements retain their ordering in the sequence. Collection classes implementing SortedSet only allow unique elements that are maintained in a sorted order. 11.4 (a) and (c) Some operations on a collection may throw an UnsupportedOperationException. This exception type is unchecked, and the code is not required to explicitly handle unchecked exceptions. A List allows duplicate elements. An ArrayList implements a resizable array. The capacity of the array will be expanded automatically when needed. The List interface defines a get() method, but there is no method by that name in the Collection interface. 11.5 (d) The program will compile without error, and will print all primes below 25 when run. All the collection implementations used in the program implement the Collection interface. The implementation instances are interchangeable when denoted by Collection references. None of the operations performed on the implementations will throw an UnsupportedOperationException. The program finds the primes below 25 by removing all values divisible by 2, 3, and 5 from the set of values from 2 through 25. Page 635
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