Mock interview 2:

What is class:

• class is a Blueprint (or) template of an object
• class is a template is used to create an objects
• class name first must be a capsletter
• It is a logical entity
• it can’t be physical

Syntax in class:

class <class name>
{
//
//
//
}

A class in java contains:

1. fields
2. methods
3. block
4. nested class and interface

What is object:

• object is memory reference of a class
• object is real time entity
• object is instantiated from class
• An entity that has state and behaviour is known as object
• It can be physical (or) logical entity

Syntax in object:

class Private       //class
{

Private pr = new Private();     //object

}

Object has three characters:

1. State–>state represents the data(value)
2. Behavior–>it represents the behavior(functionality)
3. Identity—>An object identity is typically implemented via a unique ID

What is Abstraction:

• A class which is declared with the abstract keyword is known as abstract class.
• Is a data hiding
• Showing only necessary data hiding unwanted data. Showing only functionality to the user.
• Abstract class can have main method.
• Static and non static can have an abstract class.
• we cannot create object in abstract class.
• Abstract class can have an a constructor but don’t have an object.
• if we want to access method from one to another using abstract key.
• An abstract class must be declared with an abstract keyword.
• In case inside the class one abstract method must change the class name in abstract class.

Syntax in abstraction:

Once we want to access (one to another) the abstract class(or) abstract method use the keyword (Extends)

public abstract class SmartPhone
{
int call;
public void smartphone()
{
System.out.println("smartphone ubder development");
}
public abstract int call(int seconds);
	
public abstract void sendmessage();



public abstract void receivecall();



public void browser()
{
System.out.println("SmartPhone");
}
}

public class Samsung extends SmartPhone 
{
static int price = 5000;

public static void main(String[] args)
{
Samsung sam = new Samsung();
sam.browser();
sam.sendmessage();
	sam.receivecall();
	//sam.providepattern();
}
public void sendmessage()
{
	System.out.println("messages");
}
public void receivecall()
{
	System.out.println("call");
}
}
	

Encapsulation:

• It is data protecting and data Hiding(security).
• this idea of bundling data and methods that work on data within one unit.
• the major advantage of encapsulation in java is data hiding.
• we can allow the programmer to decide on the access of data and methods.

Advantages:

(Flexible programs)–(Easy debugging and testing)–(Reusability)–(Hiding data)

Keywords in encapsulation:

Default–> default key access with in the package.

protected–>use protected key access with in the package.

public–>use public key access in any package.

private–>use private key with in class.

Example: Main reason is a data protecting and data hiding

class Bank
{ 
int interest =5;
private int salary = 5000;
public static void main(String[] args)
{
Bank rep = new Bank();
rep.deposit();
rep.withdraw();
rep.promote();
System.out.println(rep.interest);
System.out.println(rep.salary);
}
private void promote()
{
 System.out.println("Interest Activity");
}
public void deposit()
{
 System.out.println("deposit");
}
public void withdraw()
{
 System.out.println("withdraw");
}
}