CSE205 Lecture 20

Object-Oriented Programming and Data Structures
Collections
(202204)

Transcript

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   CSE 205
   Object-Oriented Programming and
   Data Structures
   Lecture 20: Collections
   Dr. Javier Gonzalez-Sanchez
   javiergs@asu.edu
   javiergs.engineering.asu.edu | javiergs.com
   PERALTA 230U
   Office Hours: By appointment
   

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   Previously
   

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3. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 3
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   I introduce you a List, a Linked List
   

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4. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 4
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   I introduce you a List, a Linked List
   

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5. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 5
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   I introduce you a List, a Linked List
   

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   Collections
   

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7. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 7
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   Definition
   § Java Collections is a framework that provides an architecture to store and
   manipulate the group of objects.
   § Java Collections can achieve all the operations that you perform on a data
   such as searching, sorting, insertion, manipulation, and deletion.
   

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8. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 8
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   Hierarchy
   

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9. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 9
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   Common methods
   § public boolean add(E e)
   § public boolean remove(E e)
   § public int size()
   § public void clear()
   § public boolean contains(Object element)
   § public boolean isEmpty()
   § And more …
   

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10. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 10
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    The interface List
    § List list1= new LinkedList();
    § List list4 = new Stack();
    § LinkedList list2 = new LinkedList();
    § Stack list4 = new Stack();
    

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11. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 11
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    LinkedList
    import java.util.*;
    public class TestJavaCollection2{
    public static void main(String a []){
    LinkedList al=new LinkedList();
    al.add(”Mary");
    al.add(”John");
    al.add(”Tom");
    al.add(”Susan");
    }
    }
    

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12. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 12
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    Stack
    import java.util.*;
    public class TestJavaCollection4{
    public static void main(String args[]){
    Stack stack = new Stack();
    stack.push(”Sun");
    stack.push(”Earth");
    stack.push(”Pluto");
    stack.push(”Saturn");
    System.out.println(stack.pop());
    System.out.println(stack.pop());
    System.out.println(stack.pop());
    }
    }
    

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13. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 13
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    PriorityQueue
    // PriorityQueue doesn't allow null values to be stored in the queue
    import java.util.*;
    public class TestJavaCollection5{
    public static void main(String args[]){
    PriorityQueue queue=new PriorityQueue();
    queue.add(”One");
    queue.add(”Two");
    queue.add(”Three");
    queue.add(”Four");
    // Retrieves, but does not remove, the head of this queue
    System.out.println("head:"+queue.element());
    System.out.println("head:"+queue.peek());
    // Retrieves and removes the head of this queue
    queue.remove();
    queue.poll();
    System.out.println("after removing two elements:");
    }
    

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    Test Yourselves
    

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15. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 15
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    What about the classes
    § Student
    § Section
    § Course
    § AcademicProgram
    

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    Nuts and bolts of Binary Trees
    Nodes
    

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17. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 17
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    What is the problem with arrays?
    

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18. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 18
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    I introduce you a List, a Linked List
    

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19. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 19
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    What about this?
    

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20. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 20
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    Binary Tree
    § A non-linear data structure
    § where each node can have 2 children at most.
    § keep the tree sorted
    

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21. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 21
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    Node
    class Node {
    public int value;
    public Node left
    public Node right;
    Node(int value){
    value = value;
    left = null;
    right = null;
    }
    }
    

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22. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 22
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    Tree | insert
    public class Tree {
    public void insert(Node node, int value) {
    if (value < node.value) {
    if (node.left != null) {
    insert(node.left, value);
    } else {
    System.out.println(" Inserted to left");
    node.left = new Node(value);
    }
    } else if (value > node.value) {
    if (node.right != null) {
    insert(node.right, value);
    } else {
    System.out.println(" Inserted to right ");
    node.right = new Node(value);
    }
    }
    }
    

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23. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 23
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    Tree | Example
    public static void main(String args[]) {
    Tree tree = new Tree();
    Node root = new Node(5);
    tree.insert(root, 2);
    tree.insert(root, 4);
    tree.insert(root, 8);
    tree.insert(root, 6);
    tree.insert(root, 7);
    tree.insert(root, 3);
    tree.insert(root, 9);
    tree.traverseLevelOrder();
    }
    }
    

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24. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 24
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    Tree | Traverse
    public void traverseInOrder(Node node) {
    if (node != null) {
    traverseInOrder(node.left);
    System.out.print(" " + node.value);
    traverseInOrder(node.right);
    }
    }
    

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25. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 25
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    Questions
    

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    CSE 205 Object-Oriented Programming and Data Structures
    Javier Gonzalez-Sanchez, Ph.D.
    javiergs@asu.edu
    Fall 2021
    Copyright. These slides can only be used as study material for the class CSE205 at Arizona State University.
    They cannot be distributed or used for another purpose.
    

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