Lists. CSC212 Lecture 8 D. Thiebaut, Fall 2014

Transcription

1 Lists CSC212 Lecture 8 D. Thiebaut, Fall 2014

2 Review List = Organization of Data in a Linear Fashion, where Order is Important Set of actions that can be carried out efficiently on the data.

3 Typical Actions Append at front, at end Insert in the middle Remove from front, from end, in middle Get the length Test if empty Iterate over all elements Sort the list

4 Can you think of a particular set of data (in every-day life) you would want to keep in a list?

5 Three Examples Road race: Keep track of arrival time for all runners (Number, Time). What operations can you imagine? List of people who List of addresses of

6 Review Vectors

7 A Note! public class Generic2 { private Object info; on Notation! public class Generic1<T> { private T info;! Generic2( Object x ) { info = x; } public String tostring() { return "info = " + info; } static public void main( String[] args ) { Generic2 n = new Generic2( (Integer) 100 );! Generic1( T x ) { info = x; } public String tostring() { return "info = " + info; } static public void main( String[] args ) { Generic1<Integer> n = new Generic1( 100 ); } } Generic2 s = new Generic2( (String) "Hello there!" ); System.out.println( n ); System.out.println( s ); Generic1<String> s = new Generic1( "Hello there!" ); } } System.out.println( n ); System.out.println( s );

8 A Small Detour Assembly Language Table ; Table[i] = 0! i 3! 14-3! 15 7

9 A Small Detour Assembly Language Table ; Table[i] = 0! i 3 mov reg, Table! 14-3 add reg, mem(i)! 15 7 mov mem(reg), 0

10 A Small Detour Assembly Language Table ; Table[i] = 0! i 3 mov reg, Table! 14-3 add reg, mem(i)! 15 7 mov mem(reg), 0 Accessing data in an array (vector) = CONSTANT TIME! ~ 3 ns

11 Evaluating the Efficiency of Vectors: Adding item at tail Adding item in front Adding item in middle Iterate over all elements Look at first item in list Look at last item in list

12 A JAVA EXAMPLE 2 Different Syntaxes

13 import java.util.iterator;! import java.util.vector;!! public class Vector2 {! static public void main( String[] args ) {! Vector<Integer> list = new Vector<Integer>( );!! for ( int i=0; i<10; i++ )! list.add( i * 3 );!!! try {! System.out.println( "Element at 4 = " + list.get( 4 ) );! } catch (ArrayIndexOutOfBoundsException e ) {! // do nothing! }!!! Iterator<Integer> it = list.iterator();! while ( it.hasnext() ) {! int x = it.next();! System.out.println( x );! }!! }! }

14 import java.util.iterator;! import java.util.vector;!! public class Vector1 {!! static public void main( String[] args ) {!!! Vector list = new Vector( );!!!! for ( int i=0; i<10; i++ )!!!! list.add( (Integer) (i * 3) );!!!!!! try {!!!! System.out.println( "Element at 4 = " + list.get( 4 ) );!!! } catch (ArrayIndexOutOfBoundsException e ) {!!!! // do nothing!!! }!!!!!!! Iterator<Integer> it = list.iterator();!!! while ( it.hasnext() ) {!!!! int x = it.next();!!!! System.out.println( x );!!! }!! }! }

15 LINKED-LISTS (Chapter 3 in Drozdek)

16 head tail info next info next info next info next

17 head tail info next info next info next info next

18

19 info next class intsllnode {!!! public int info;! public intsllnode next;!!! public intsllnode( int i ) {! this( i, null );! }! public intsllnode( int i, intsllnode n ) {! info = i;! next = n;! }! }

20 Questions: How do we implement a Linked List in Java, once we have intsslnode? What is an empty list? How do we mark the end of a list? How do we add an element at the front? How do we add an element at the end (tail)? How do we remove an element from the front? From the end?

21 public class IntSLList {!! protected IntSLLNode head, tail;!! public IntSLList () {!!! head = tail = null;!! }!! public boolean isempty() {!!! return (head == null);!! }!! public void addtohead( int x ) {!!! head = new IntSLLNode( x, head );!!! if ( tail==null )!!!! tail = head;!! }!! public int deletefromhead() {!!! int el = head.info();!!! if ( head==tail )!!!! head = tail = null;!!! else head = head.next;!!! return el;!! }!! // continues on Page 84 in Drozdek! }

22 Evaluating the Efficiency of Linked Lists: Adding item at tail Adding item in front Adding item in middle Iterate over all Look at first item in list Look at last item in list

23 Doubly-Linked Lists: Removing Some of the Inefficiencies of Singly-Linked Lists

24 head tail info next prev info next prev info next prev info next prev

25 Class Exercise

26

27 LIST Modularization OOP Encapsulation

28 Java Lists: Vector ArrayList LinkedList

29 import java.util.linkedlist;!! class LinkedListExample {!!! public static void main(string[] args) {! // create a new linked list! LinkedList L = new LinkedList();!! // add 5 integers to it.! for ( int i=10; i<=50; i+= 10 )! L.addFirst( i );!! // display contents of list! System.out.println( L ); // <==?! }! } LinkedList

30 import java.util.arraylist;! public class ArrayListExample { public static void main(string[] args) { // create a new linked list ArrayList L = new ArrayList(); // add 5 integers to it. for ( int i=10; i<=50; i+= 10 ) L.add( i ); } } // display contents of list System.out.println( L ); // <==? ArrayList

31 Stacks & Queues

32 Queue First In First Out = FIFO

33 Operations dequeue() enqueue() isempty() NOTE: Queue is an interface to LinkedLists. We'll skip examples of how to use them! for right now

34 In Kyung Lee (Inky), Kinect, and Queues Photo from

35 Inky's movie Inky's choreography DT on fire Research and Special Effects Based_Choreography

36 JAVA PROGRAM

37 JAVA THREAD JAVA THREAD

38 JAVA THREA D JAVA THREA D Keywords: Threads Asynchronous Synchronized Data Structures

39 Stack Push() Pop() Top() isempty() Last In First Out = LIFO

40 import java.util.stack;! public class StackExample {! public static void main(string[] args) { Stack stack = new Stack(); for ( int i=10; i<= 50; i+=10 ) { System.out.println( "\npushing " + i ); stack.push( i ); System.out.println( "The top of the stack is now " + stack.peek() ); } System.out.println( "\nstack: bottom --> " + stack + " <-- top\n" ); } } while (! stack.isempty() ) { int x = (int) stack.pop(); System.out.println( "Just popped " + x ); System.out.println( "The stack now contains " + stack.size() + " elements"); }

41 Reverse Polish Notation