CSS446 Spring 2014 Nan Wang

 Java Collection Framework ◦ Stack ◦ Queue & Priority Queue 2

 A hierarchy of interface types and classes for collecting objects. Each interface type is implemented by one or more classes. 3

 A stack remembers the order of its elements, but it does not allow you to insert elements in every position.  You can add and remove elements only at the top. 4

 A stack is a collection of elements with last- in, first-out retrieval (LIFO).  Undo feature in word processor  Run-time stack that a processor or virtual machine keeps to store the values of variable in nested methods. 5

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 In a queue, you add items to one end (the tail) and remove them from the other end (the head).  A priority queue is an unordered collection that has an efficient operation for removing the element with the highest priority. (reading assignments) 8 Bus Stop front rear

 A Queue is a collection of elements with first- in first-out retrieval.  Print queue 9

 A priority queue collects elements, each of which has a priority.  Elements are retrieved according to their priority.  New elements can be inserted in any order.  Removing an element from a priority queue, the element with the most urgent priority is retrieved. 10

 Because the priority queue needs to be able to tell which element is the smallest, the added elements should belong to a class that implements the Comparable interface!!! 11

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 Java How to Program 9 th  Chapter 7,8,9,10, 11,18,20 review questions  Big Java  Chapter 7-13,15 Review Questions 13

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