java collection

1. OOP / Slide 1
Collection Framework

2. OOP / Slide 2
Reduces programming effort
>Increases program speed and quality
>Reduce effort to learn and use new APIs
 Is simply an object that groups multiple elements
into a single unit.
 Sometimes called a container
 Collections are used to store, retrieve, manipulate,
and communicate aggregate data
Benefits of Collection Framework
What is a Collection?

3. OOP / Slide 3
The Collections Hierarchy

4. OOP / Slide 4
Collection Framework
 ArrayList Class
 LinkedList Class
 HashSet Class
 LinkedHaseSet Class
 TreeSet Class
 Map Interface
 LinkedHashMap Class
 TreeMap Class
 Hashtable Class
 Comparable Interface
 Comparator Interface
 HashMap Class

5. OOP / Slide 5
Commonly thrown Exceptions in Collection Framework
 UnSupportedOperationException
 occurs if a Collection cannot be modified.
 ClassCastException
 occurs when one object is incompatible with another.
 NullPointerException
 occurs when you try to store null object in Collection.
 IllegalArgumentException
 thrown if an invalid argument is used.
 IllegalStateException
 thrown if you try to add an element to an already full Collection.

6. OOP / Slide 6
Hierarchy of ArrayList class:
ArrayList<Integer> list = new ArrayList<Integer>(0);
list.add(1001);
list.add(1002);
System.out.println(list.get(5));
Exception:
java.lang.IndexOutOfBoundsException:
Index: 4, Size: 2
IndexOutOfBoundsException

7. OOP / Slide 7
ArrayList class:
 Uses a dynamic array for storing the elements.It extends
AbstractList class and implements List interface.
 Can contain duplicate elements.
 It Maintains insertion order.
 Not synchronized.
 Random access because array works at the index basis.
 Manipulation slow because a lot of shifting needs to be
occurred.

8. OOP / Slide 8
Methods of Collection interface
public boolean equals(Object element) : matches two collection.

9. OOP / Slide 9
Example of addAll(Collection) method:

10. OOP / Slide 10
Example of removeAll() method:

11. OOP / Slide 11
Example of retainAll() method:

12. OOP / Slide 12
By Iterator interface.
package Collection;
import java.util.ArrayList;
import java.util.Iterator;
public class Array1 {
public static void main(String[] args) {
ArrayList alist=new ArrayList();
alist.add("Ravi");
alist.add("Vijay");
alist.add("Ravi");
Iterator itr=alist.iterator();
while(itr.hasNext()){
System.out.println(itr.next());
} }}
Output:
Ravi
Vijay
Ravi

13. OOP / Slide 13
ArrayList: By for-each loop.

14. OOP / Slide 14
LinkedList class:
 Uses doubly linked list to store the elements. It extends the
AbstractList class and implements List and Deque
interfaces.
 Can contain duplicate elements.
 Maintains insertion order.
 Not synchronized.
 No random access.
 Manipulation fast because no shifting needs to be occurred.

15. OOP / Slide 15
Difference between List and Set:
List can contain duplicate elements
whereas
Set contains unique elements only.

16. OOP / Slide 16
Linked List

17. OOP / Slide 17
HashSet class:
 Uses hashtable to store the elements.It extends
AbstractSet class and implements Set interface.
 contains unique elements only.
HashSet hs=new HashSet();
hs.add("Ravi");
hs.add("Vijay");
Iterator itr=hs.iterator();
while(itr.hasNext()){
System.out.println(itr.next());
Output:
Ravi
Vijay

18. OOP / Slide 18
TreeSet class:
1. Contains unique elements
only like HashSet.
2. The TreeSet class
implements NavigableSet
interface that extends the
SortedSet interface.
3. Maintains ascending order.

19. OOP / Slide 19
Treeset
Output:
Ravi
vijay

20. OOP / Slide 20
HashMap
 A HashMap contains values based on the key. It implements
the Map interface and extends AbstractMap class.
 It contains only unique elements.
 It may have one null key and multiple null values.
 It maintains no order.

21. OOP / Slide 21
HashMap class:
Hierarchy of HashMap
 What is difference
between HashSet and
HashMap?
HashSet contains only
values whereas HashMap
contains entry(key and
value).

22. OOP / Slide 22
HashMap

23. OOP / Slide 23
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