1. Advanced Java FDP
on 12th June, 2017

2. Today’s Agenda Java Brush-up Session Data structures in Java
Collections in Java
Generics in Java
Serialization in Java
Networking
Database Connectivity with Java
Multithreading in Java
Java UI

3. Object
An entity that has state, behaviour and identity is called as object.
E.g.: pen, chair, table, keyboard, etc.
Syntax:
<Class Name> <identifier name>= new <Class Name>();
Example:
Student object = new Student();

4. Class Collection of objects is called as class. It is a logical entity
Syntax:
class <Class Name>{
//data members }
Example:
class Student{
int rollNo;
String name;
void studies(){
System.out.println(“Student Studies”);

5. Interface Completely incomplete class 100% incomplete class
Just has method declaration
No constructor, no instance variables
Cannot create object of Interface using new keyword directly
Used in designing frameworks
E.g.:
interface RBI{
public int getRateOfInterest(); }

6. Abstract Class Partially incomplete class 0% to 100% incomplete class
Few methods are complete while few are incomplete
Cannot create object of abstract class directly using new keyword
Used in designing frameworks
E.g.:
abstract class Bike{
abstract int speed();
public void start(){
System.out.println(“Starting”); }
Note: Abstract class can be an interface but not vice-versa

7. Inheritance
When one object acquires all the properties and behaviour of parent object is known as inheritance
Provides code reusability
Class as Parent –
class Child extends Parent
Interface as Parent –
class Child implements Parent

8. Polymorphism
When one task is performed by different ways is known as polymorphism.
Polymorphism is achieved by –
Method Overloading
Method Overriding

9. Abstraction
Hiding internal details and showing functionality is known as abstraction
For example: Phone call, we don’t know the internal details
We use abstract class and interface to achieve abstraction

10. Encapsulation
Binding (or wrapping) code and data together into a single unit is known as encapsulation.
A Java class is an example of encapsulation
For example: Capsule, it is wrapped with different medicines

11. Naming Convention Name Convention class name
should start with uppercase letter and be a noun e.g. String, Color, Button, System, Thread etc.
interface name
should start with uppercase letter and be an adjective e.g. Runnable, Remote, ActionListener etc.
method name
should start with lowercase letter and be a verb e.g. actionPerformed(), main(), print(), println() etc.
variable name
should start with lowercase letter e.g. firstName, orderNumber etc.
package name
should be in lowercase letter e.g. java, lang, sql, util etc.
constants name
should be in uppercase letter. e.g. RED, YELLOW, MAX_PRIORITY etc.

12. Java Package Package can be considered similar to folder
Package can hold -
Sub-packages
Similar classes
Similar interfaces
Advantages:
Used to categorize the classes and interfaces so that they can be easily maintained
Provides access protection
Removes naming collision

13. Sample Java Program Sample Code - package com.main; class HelloWorld{
public static void main(){
System.out.println(“Hello World”); }
Compile:
javac -d . HelloWorld.java
Execute:
java com.main.HelloWorld

14. Pre-session intructions
How to create project in Eclipse?
How to create package in Eclipse?
How to create class in Eclipse?
How to run a program in Eclipse?
Create 2 different projects –
SampleProject
Assignments

15. END OF ‘Java Brush up Session’

16. Data Structures in Java
Is a particular way of organizing objects so that they can be used efficiently
DS are provided by java utility package
Very powerful
Perform wide range of functionalities

17. Data Structures in Java continued...
It encompasses –
Enumeration
BitSet
Vector
Stack
Dictionary
Hashtable
Properties
But all these classes are legacy now
All are replaced by new framework Collections

18. Enumeration Interface
Isn’t itself a Data Structure
Defines the methods by which we can enumerate the elements in collection of objects
Has been superseded by Iterator
Methods –
boolean hasMoreElements()
Object nextElment()

19. BitSet Class (Refer Example1)
Creates a special type of array that holds bit values.
Can increase in size as needed
Constructor –
BitSet()
BitSet(int size)
26 methods, some of them are Methods-
void and(BitSet bitSet)
void or(BitSet bitSet)
void set(int index)
boolean isEmpty()
void flip(int index)
boolean get(int index)

20. Vector Class (Refer Example2)
Implements a dynamic array
Similar to Array List with 2 differences –
Vector is synchronized
Contains many legacy methods
Provides to be very useful if size of array is not known
It can shrink and grow automatically using increment property
Re-engineered in Collection Framework

21. Vector - Constructor & Methods
Constructors –
Vector()
Vector(int size)
Vector(int size, int incr)
Vector(Collection c)
42 Methods, some of them are –
void addElement(Object obj)
int capacity()
void clear()
boolean contains(Object obj)
Enumeration elements()
Object firstElement()
Object remove(int index)

22. Stack Class (Refer Example3)
Is a sub-class of vector
Implements standard last-in, first-out stack
Re-engineered in Collection framework
Constructor –
Stack()
Includes all methods of vectors and few of its own –
boolean empty()
Object peek()
Object pop()
Object push(Object element)
int search(Object element)

23. Dictionary Abstract Class
Represents a key-value storage repository
Once the value is stored can be retrieved using key
Similar to Map
Methods –
Enumeration elements()
Object get(Object Key)
boolean isEmpty()
Enumeration keys()
Object put(Object key, Object value)
Object remove(Object key)
int size()

24. Hashtable Class (Refer Example4)
Is a concrete implementation of Dictionary
Stores key-value pairs
The key is hashed, and the resultant hashcode is the index where the value is stored
Re-engineered in Collection Framework

25. Hashtable – constructors and methods
Hashtable(int size)
Hashtable(int size, float fillRatio)
Hashtable(Map<? extends K, ? extends V > t)
Methods (All methods from Dictionary and few of its own)-
void clear()
Object clone()
boolean contains(Object value)
boolean containKey(Object key)
void rehash()

26. Properties Class (Refer Example5)
Is a sub-class of Hashtable
Used to maintain key-value pairs where key and value both are String
Constructors –
Properties()
Properties(Properties getDefault)
All methods from Hashtable and few of its own –
String getProperty(String key)
void list(PrintStream streamOut)
void load(InputStream streamIn) throws IOException
Enumeration propertyNames()
Object setProperty(String key, String value)

27. END OF ‘Java Data Structures’

28. Collections Framework in Java
Is a framework that provides an architecture to store and manipulate the group of objects
All the operations can be performed on the group of objects as like data
Simply means a single unit of object
Interfaces in Collection framework–
List, Set, Queue, Dequeue
Classes implementing above interfaces –
ArrayList, LinkedList, Vector, PriorityQueue, HashSet,
LinkedHashSet, TreeSet, etc.

29. Goals achieved by Collection Framework
High Performance Framework
Highly Efficient
Allows different types of collections to work in a similar manner (central, unifying theme)
High degree of interoperability
One collection can adapt/extend other collection easily

30. Hierarchy of Collection Framework

31. Iterator Interface
Provides the facility of iterating the elements in forward direction only
Methods-
public boolean hasNext()
public Object next()
public void remove()

32. Collection Interface Methods – public boolean add(Object element)
public boolean addAll(Collection c)
public boolean remove(Object element)
public boolean removeAll(Collection c)
public boolean retainAll(Collection c)
public int size()
public void clear()
public boolean contains(Object element)
pubic boolean containsAll(Collection c)
public Iterator iterator()
public Object[] toArray()
public boolean isEmpty()
public boolean equals(Collection c)
public int hashCode()

33. List Interface Is a sub-interface of Collection interface
It contains method to insert and delete elements on index basis
Methods –
public void add(int index, Object o)
public boolean addAll(int index, Collection c)
public Object get(int index)
public Object set(int index, Object o)
public Object remove(int index)
public ListIterator listIterator()
public ListIterator listIterator(int index)

34. ArrayList Class (Refer Example6)
Uses a dynamic array for storing the elements
Inherits AbstractList class and implements List interface
Important Points –
Can contain duplicate elements
Maintains insertion order
Is non-synchronized
Allows random access because array works at the index basis
Manipulation is slow since, shifting of elements occur on deletion of any element

35. ArrayList – Constructors and Methods
ArrayList(Collection c)
ArrayList(int capacity)
Methods –
void add(int index, Object element)
boolean addAll(Collection c)
void clear()
int lastIndexOf(Object o)
Object[] toArray()
boolean add(Object o)
Object clone()
int indexOf(Object o)
void trimToSize()

36. LinkedList Class (Refer Example7)
Uses doubly linked list to store the elements
It extends the AbstractList class and implements List and Deque interfaces
Important Points –
Can contain duplicate elements
Maintains insertion order
Is non-synchronized
Manipulation is fast because no shifting needs to be occurred
Can be used as list, sack or queue

37. LinkedList – Constructor and Methods
LinkedList(Collection c)
Methods –
void add(int index, Object element)
void addFirst(Object o)
void addLast(Object o)
int size()
boolean add(Object o)
boolean contains(Object o)
boolean remove(Object o)
Object getFirst()
Object getLast()
int indexOf(Object o)
int lastIndexOf(Object o)

38. ArrayList v/s LinkedList
Uses Dynamic Array to store elements
Uses doubly linked list to store elements
Manipulation is slow
Manipulation is fast
Can act as list only
Can act as list and queue both
Better for storing and accessing
Better for manipulating data

39. HashSet Class (Refer Example8)
Used to create a collection that uses a hash table for storage
Inherits AbstractSet class and implements Set interface
Important Points –
Stores elements by hashing
Contains unique elements only
Does not main insertion order
Difference between List and Set
List can contain duplicate elements
Set contains unique elements only

40. HashSet – constructor and methods
HashSet(Collection c)
HashSet(int capacity)
Methods –
void clear()
boolean contains(Object o)
boolean add(Object o)
boolean isEmpty()
boolean remove(Object o)
Object clone()
Iterator iterator()
int size()

41. LinkedHashSet class (Refer Example9)
Is a hash table and linked list implementation of the Set interface
Inherits HashSet class and implements Set interface
Important Points –
Contains unique elements
Permits null elements
Maintains insertion order

42. LinkedHashSet - constructor and methods
HashSet(Collection c)
LinkedHashSet(int capacity)
LinkedHashSet(int capacity, float fillRatio)
Methods –
All methods of HashSet

43. TreeSet Class (Refer Example10)
Implements the Set interface which uses a tree for storage
Inherits AbstractSet class and implements NavigableSet interface
Objects of TreeSet class are stored in ascending order
Important Points –
Contains unique elements
Access and retrieval times are quite fast
Maintains in ascending order

44. TreeSet – constructor and methods
TreeSet(Collection c)
TreeSet(Comparator comp)
TreeSet(SortedSet ss)
Methods –
boolean addAll(Collection c)
boolean contains(Object o)
boolean isEmpty()
boolean remove(Object o)
void add(Object o)
void clear()
Object clone()
Object first()
Object last()
int size()

45. Queue Interface Orders the element in the FIFO manner Methods –
boolean add(Object o)
boolean offer(Object o)
Object remove()
Object poll()
Object element()
Object peek()

46. PriorityQueue Class (Refer Example11)
Provides the facility of using queue
But does not orders the elements in FIFO order
Inherits AbstractQueue class
Methods –
Same as Queue interface

47. Deque interface
Is a linear collection that supports element insertion and removal at both ends
It represents Double Ended Queue
Methods –
boolean add(Object o)
boolean offer(Object o)
Object remove()
Object poll()
Object element()
Object peek()

48. ArrayDeque Class (Refer Example12)
Provides the facility of using deque and resizable-array
Inherits AbstractCollection class and implements Deque interface
Important Points –
Can add and remove elements from both ends
Null elements are not allowed
Not thread safe
No capacity restriction
Is faster than LinkedList and Stack

49. Map Interface Contains values on the basis of key
Each key-value pair is called as an entry
Map contains only unique keys
Useful if we have to search, update and delete on the basis of key
Methods –
Object put(Object key, Object value)
void putAll(Map map)
Object remove(Object key)
Object get(Object key)
boolean containsKey(Object key)
Set keySet()
Set entrySet()

50. Map.Entry interface Entry is a sub-interface of Map
Hence, should be accessed as Map.Entry
Provides methods to get key and value
Methods –
Object getKey()
Object getValue()

51. HashMap Class (Refer Example13)
Implements Map interface by using a hashtable
Inherits AbstractMap class and implements Map interface
Important Points –
Contains value based on the key
Only unique elements
Have one null key and multiple null values
Maintains no order

52. HashMap – constructors and methods
HashMap(Map m)
HashMap(int capacity)
HashMap(int capacity, float fillRatio)
Methods –
void clear()
boolean containsKey(Object key)
boolean containsValue(Object value)
boolean isEmpty()
Object clone() Set entrySet()
Set keySet()
Object put(Object key, Object value)
int size()
Collection values()

53. LinkedHashMap Class (Refer Example14)
Is a Hash table and Linked List implementation of Map
It inherits HashMap class and implements Map interface
Important Points –
Contains values based on key
Contains only unique elements
May have one null key and multiple null values
Same as HashMap instead maintains insertion order

54. LinkedHashMap – constructor and methods
LinkedHashMap(int capacity)
LinkedHashMap(int capacity, float fillRatio)
LinkedHashMap(Map m)
Methods –
Object get(Object key)
void clear()
boolean containsKey(Object key)

55. TreeMap Class (Refer Example15)
Implements the Map interface by using tree
Provides an efficient means of storing key- value pairs in sorted order
Implements the NavigableMap interface and extends AbstractMap class
Important Points –
Contains only unique element
Cannot have null key but can have multiple null values
Same as HashMap instead maintains ascending order

56. TreeMap – constructor and method
TreeMap(Comparator comp)
TreeMap(Map m)
TreeMap(SortedMap sm)
Methods –
boolean containsKey(Object key)
boolean containsValue(Object value)
Object firstKey()
Object get(Object key)
Object lastKey()
Object remove(Object key)
void putAll(Map map)
Set entrySet()
int size()
Collection values()

57. HashMap v/s TreeMap HashMap TreeMap Can contain one null key
Cannot contain any null key
Maintains no order
Maintains ascending order

58. HashMap v/s HashTable HashMap Hashtable
Non-synchronized, hence not thread safe
Synchronized, hence thread safe
Allows one null key and multiple null values
Neither key nor value null is allowed
Newly introduced
Legacy class
Fast
Slow
Traversed by Iterator
Traversed by Enumerator and Iterator
Inherits AbstractMap class
Inherits Dictionary class

59. END OF ‘Collection Framework’

60. Generics in Java Introduced to deal with type-safe objects
Before generics -> able to store any type of objects in collection
After generics -> forces to store specific type of objects in collection
Advantages –
Type-safety
Type casting is not required
Compile-Time checking
Syntax –
ClassORInterface<Type>
Example –
ArrayList<String>

61. Generic Class (Refer Example16)
A class that can refer to any type is known as generic class
Example –
class MyGen<T>{
T obj;
void add(T obj){
this.obj = obj; }
T get(){
return obj;
‘T’ indicates that class can refer to any type (like String, Integer, Employee, etc.)

62. Type Parameters
T – Type
E – Element
K – Key
N – Number
V - Value

63. Generic Method (Refer Example17)
A method that can accept any type of argument is called as Generic method
Example –
class TestGenerics{
public <E> void printArray(E[] elements){ }

64. Wild Card in Generics (Refer Example18)
The ? (question mark) symbol represents Wild card element
It means any type
If we write <? extends Number>, it means any child class of Number
Take Example

65. END OF ‘Generics in Java’

66. Serialization in Java
Is a mechanism of writing the state of an object into a byte stream
Mainly used in Hibernate, RMI, JPA, EJB and JMS technologies
Reverse operation is know as Deserialization

67. Advantages of Serialization
Mainly used to travel object’s state on network (Known as Marshalling)

68. Serializable interface
Belongs to java.io package
Is a marker interface
What is marker interface?
Has no data member and no method is defined
Used to “mark” java classes so that objects of that class may get certain capability
Cloneable and Remote also are marker interfaces
So if a class is marked Serialize, its object can be converted to stream

69. Example Serializable Student Example
Student class implements Serializable interface
Hence marked as Serializable
Its objects can be converted into Stream

70. How to convert objects into stream?
Converting object into stream is Serialization
ObjectOutputStream class is used to –
write primitive data types to an OutputStream
Java objects to an OutputStream
Only objects of classes which are marked Serializable are supported
Example of writing Student object to File

71. How to convert stream into object?
Converting stream back to object is Deserialization
Deserialization is process of reconstructing the object from the serialized state
ObjectInputStream class is used to –
Deserialize java objects which are serialized by ObjectOutputStream
Deserialize prmitive data type which written using ObjectOutputStream
Example of Deserializing Student object from File

72. END OF ‘Serialization in Java’