Chapter 22 Java Collections Framework.doc

Chapter 22 Java Collections Framework The Java Collections Framework defines the Java API for handling common data structures tasks in Java. It defines classes and interfaces for storing and manipulating data in sets, lists, and maps. A convenience class is an abstract class that partially implements an interface. The Java Collections Framework defines interfaces, convenience abstract classes, and concrete classes. Yes. The concrete classes of Set, List, and Map implements the clone() method in the Cloneable interface. addAll(Collection c). If a method has no meaning in the subclass, you can implement it in the subclass to throw java.lang.UnsupportedOperationException, a subclass of RuntimeException. This is a good design that you can use in your project. If a method has no meaning in the subclass, you can implement it as follows: The Set is an interface. To create an instance of Set, you need to use HashSet or TreeSet. To insert an element to a set, use the add method. To remove an element from a set, use the remove method. To find the size of a set, use the size() method. HashSet is unsorted, but TreeSet is sorted. HashSet is more efficient than TreeSet if you don’t want the elements in a set to be sorted. If you create a TreeSet using its default constructor, the compareTo method is used to compare the elements in the set, assuming that the class of the elements implements the Comparable interface. To use a comparator, you have to use the constructor TreeSet(Comparator comparator) to create a sorted set that uses the compare method in the comparator to order the elements in the set. A runtime error would occur if you add an element that cannot be compared with the existing elements in the tree set? To traverse a set, use the iterator method to obtain an iterator. You can then traverse the set through the iterator. Using an iterator, you can traverse only sequentially from the beginning to the end. To sort the elements in a set using the Comparable interface, th