My Project Architecture is divided into Three Layers.
        

1. Presentation Layer (Client or Browser).
2. Business Layer. (Frameworks and Logical). 
3. Database Layer. (Like: Oracle/SQL/Mysql). 

Presentation Layer (Client or Browser): it is also known as client layer (Like UI). The main functionality of this layer is to communicate with Application layer.
Business Layer (Frameworks and Logical): It is also called business logic layer interacts with database layer and send required information to the presentation layer.
Database Layer. (Like: Oracle/SQL/Mysql):The Data is stored in the Layer. Business layer communication with database layer to retrieve insert, update, delete the data.

Project Process: When ever we submitting the request from client to server component then controller receives the request from browser . so you mast remember every request will reach to controller component.
The controller receives the request from browser then controller has to identity a particular model. then it will execute be java class or business logic's available. Hence: Here controller acts as mediator between view and the model.
After executing model part if it is required to interact with database then model part interact with data.
Then view layer display of the model to the end user. then generated the require dynamic web page return to browser. finally view part send to the response to the client.

Q.1:   Is the code compiles ? If yes then what will be the output ?
Ans.
class IntegerValue { public static void main(String[] args) { Integer i1 = 128; Integer i2 = 128; System.out.println(i1 == i2); Integer i3 = 127; Integer i4 = 127; System.out.println(i3 == i4); } } Output :      false
                  true
Q.2: Is the code compiles ? If yes then what will be the output ?
Ans.
class a{ static{System.out.println("s1");} public String GetCityname(String s){ return "String"; } } class b extends a{ static{System.out.println("s2");} public String GetCityname(String s1){ return "StringBuffer"; } } public class LogicTest extends b{ static{System.out.println("s3");} public static void main(String[] args) { System.out.println("post"); LogicTest o=new LogicTest(); System.out.println(o.GetCityname("mano")); System.out.println("stop"); } } Output :      s1
                  s2
                  s3
                  post 
                 StringBuffer 
                 stop
Q.3: Is the code compiles ? If yes then what will be the output ?
Ans.
class StaticDemo{ static { i=10; System.out.println("r10"); } static { i=11; System.exit(0); } static int i; public static void main(String[] args) { StaticDemo obj= new StaticDemo(); obj.i=20; System.out.println("i= "+StaticDemo.i); } }
Output :   r10
Q4. : Is the code compiles ? If yes then what will be the output ?
Ans.
class equal{ public void run(){ String s1="manoj"; String s2=new String("manoj"); if(s1==s2){ System.out.println("run method output: S1==S2 is True"); }else if(s1.equals(s2)){ System.out.println("run method output: s1.equals(s2) is true"); } else{ System.out.println("run method output: Not equals"); } } public void run1(){ String s1="manoj"; s1.concat("kumar1434@gmail.com"); String s2="manoj"; if(s1==s2){ System.out.println("run1 method output: S1==S2 is True"); }else if(s1.equals(s2)){ System.out.println("run1 method output: s1.equals(s2) is true"); } else{ System.out.println("run1 method output: Not equals"); } } } public class StringEqualAppend { public static void main(String[] args) { equal resul=new equal(); resul.run(); resul.run1(); } }
Output:          run method output: s1.equals(s2) is true
                     run1 method output: S1==S2 is True
Q.5:Is the code compiles ? If yes then what will be the output ?
Ans.
class logiTest { public static void main(String[] args) { int i=1; if(i++>1) System.out.println(i--); else System.out.println(i++); } }
Output :   2
Q.6:Is the code compiles ? If yes then what will be the output ?
Ans.
class nullPoint { public static void main(String[] args) { Integer i=null; int j=i; System.out.println(j); } }
Output :          java.lang.NullPointerException.
Q. 7: Is the code compiles ? If yes then what will be the output ?
Ans.
class test1 { public static void main(String[] args) { String s3 = "Hello Manoj"; int start = 4; char end = 11; System.out.println(start + end); System.out.println(s3.substring(start, end)); } }
Output:         15
                    o Manoj
Q.8: Is the code compiles ? If yes then what will be the output ?
Ans.
class A{ static int a = 9999; static { a = a-- - --a; System.out.println("Run1---: "+a); } static { a = a++ + ++a; System.out.println("Run2+++: "+a); } public static void main(String[] args) { System.out.println("Run Main Body : "+a); } }
Output :     Run1---: 2
                 Run2+++: 6
                 Run Main Body : 6
Q.9: Is the code compiles ? If yes then what will be the output ?
Ans.
class testDemo { public int number(int n) { System.out.println("public int"); return n; } protected Integer number(Integer n) { System.out.println("protected int"); return n; } protected Object number(Object n){ System.out.println("object"); return n;} private String number(String d) { System.out.println("String"); return "n"; } public static void main(String[] args) { testDemo n12 = new testDemo(); n12.number(10); n12.number(785.68); n12.number("manojkumar"); int a[]={10,20,30,05}; int b; b=a.length; System.out.println(b); } }
Output :             public int
                         object
                         String
                         4

Q.1- What is OOPs ?
Ans.- OOps(Object Oriented Programming System) is a Methodology to design a Program using class and Object is known as a OOps.
Q.2- What is Concepts of OOps ?
Ans.- There are following Concepts.

1.   Object.
2.   Class.
3.   Inheritance.
4.   Polymorphism.
5.   Encapsulation.
6.   Abstraction.

Q. 3- What is Object?
Ans.- Any Entity that has state and behavior is Called object. it can be Physical and Logical.
Q. 4- What is Class?
 Ans.- Class is Collection of object is Called Class. it is Logical Entity.
Q.5- What is Inheritance ?
Ans.- When one object Acquires all the Properties and behaviors of parent object is Called Inheritance. It provides code re-usability. it is used to achieve run-time Polymorphism.
Q.6- What is Polymorphism?
Ans.- When one Task is Performed to different way is known as a Polymorphism. in java, we  use Method Overloading and Overriding to achieve Polymorphism.
Q.7- What is Encapsulation?
Ans.-Encapsulation is the process of binding or wrapping code and data together into a single unit is Called Encapsulation. java beans is the fully of encapsulation class because all data members are private here.
Q.8- What is Abstraction?
Ans.- Abstraction is the process of Hiding internal details and showing functionality is Called Abstraction.
In java, we use abstract class and interface to achieve abstraction.
Example- Phone Call.
Q.9- Is the code compiles ? If yes then what will be the output ?

class testDemo { public Integer number(int n) { System.out.println("Integer"); return n; } protected Integer number(Integer n) { System.out.println("int"); return n; } protected Object number(Object n){ System.out.println("Object"); return n;} public static void main(String[] args) { testDemo n12 = new testDemo(); n12.number(10); n12.number("o"); int a[]={10,20,30,05}; int b; b=a.length; System.out.println(b); } }
Ans.-                         Integer
                                 Object
                                  4
Q.10- Is the code compiles ? If yes then what will be the output ?
1. class is over.java
class over { protected int add(int a){ System.out.println("add"); return a; } }
2. class is overTest.java
class overTest extends over{ public Integer add(Integer a){ System.out.print("add1"); return a; } public static void main(String[] args) { overTest o=new overTest(); o.add(11); } }
Ans.-       add.
Q.11- Is the code compiles ? If yes then what will be the output ?
1. class is over.java
interface A { void a(); void b(); void c(); void d(); } abstract class B implements A{ public void c(){ System.out.println("I am c"); } } class M extends B{ public void a() { System.out.println("I am A"); } public void b() { System.out.println("I am B"); } public void d() { System.out.println("I am D"); } } class testMain{ public static void main(String[] args) { A a1=new M(); a1.a(); a1.b(); a1.c(); a1.d(); } }
Ans.-      I am A
              I am B
              I am c
              I am D.
Q.12- Is the code compiles ? If yes then what will be the output ?
class Test{ public static void main(String[] args) { int a=100, b=200; while(++a<--b); System.out.println(+a); System.out.println(+b); } }
Ans.-                     150
                             150

Q. 1- Is the code compiles ? If yes then what will be the output ?
public class supper { int i; public int getI() { return i; } public void setI(int i) { this.i = i; } public static void main(String[] args) { supper obj=new supper(); obj.setI(3); System.out.println(obj.getI()); supper b=obj; b.setI(4); System.out.println(b.getI()); } }
Output is:    3 4
Q. 2-Is the code compiles ? If yes then what will be the output ?
public class Consoletest{ public static void main(String[] args) { Console c=System.console(); System.out.println(c); } }
Output is:       null
Q. 3-Is the code compiles ? If yes then what will be the output ?
public class salesInvoices{ public static String formateID(String oldid){ return oldid+"_selsinvers"; } public static void main(String[] args) { salesInvoices s=new salesInvoices(); System.out.println( s.formateID("Hello")); } }
Output is:     Hello_selsinvers
Q. 4-Is the code compiles ? If yes then what will be the output ?
class Thing { public static int number_of_things = 0; public String what; public Thing (String what) { this.what = what; number_of_things++; System.out.println(number_of_things++ +","+what); } protected void finalize () { number_of_things--; } } public class TestDestructor { public static void main(String[] args) { Thing obj = new Thing("Test App"); } }
Output is:      1, Test App
Q. 5-Is the code compiles ? If yes then what will be the output ?
public class test { public static void main(String [] args) { try { badMethod(); System.out.print("A"); } catch (Exception ex) { System.out.print("B"); } finally { System.out.print("C"); } System.out.print("D"); } public static void badMethod() { throw new Error(); /* Line 22 */ } }
Output is:  Error in line number is 22 for java.lang.Error Then after output is C
Q. 6-Is the code compiles ? If yes then what will be the output ?
class newgensogt extends Thread { int code = 9; public void run() { this.code = 7; } public static void main(String[] args) { newgensogt n = new newgensogt(); n.start(); for (int i = 0; i < 5; i++) { System.out.println(n.code); } } }
Output is:     9 7 7 7 7
Q. 7-Is the code compiles ? If yes then what will be the output ?
class ex { static String r=""; public static void main(String[] args) { try { r+="1"; throw new Exception(); } catch (Exception e) { r+="2"; } finally{ r+="3"; dispaly();} System.out.println(r); } private static void dispaly() { int x=0; int y=7/x; /* Line 17 */ } }
Output is:   Error in line number is 17 for java.lang.ArithmeticException: / by zero

Q. 8-Is the code compiles ? If yes then what will be the output ?
class ntEX { static int i=1, k=2; static { display(i); } public static void main(String[] args) { ntEX obj=new ntEX(); display(k); obj.display(i); } static void display(int n) { System.out.println(n); } }
Output is:   1 2 1
Q. 9-Is the code compiles ? If yes then what will be the output ?
class subStringCons{ public static void main(String args[]){ byte b[]={77,65,78,79,74}; String s1=new String(b); System.out.println(s1); String s2=new String(b, 2, 3); System.out.println(s2); } }
Output is:             MANOJ
                                 NOJ
Q. 10-Is the code compiles ? If yes then what will be the output ?
class subString{ public static void main(String args[]){ String s="abc"; String s1=new String("abc"); if(s==s1){ System.out.println("1 String is Equals"); }else if(s.equals(s1)){ System.out.println("2 String is Equals"); }else{ System.out.println("String is not Equals");} } }
Output is:         2 String is Equals

• Bootstrap Class Loader. 
• Extension Class Loader. 
• System Class Loader.
• Plugin Class Loader.

Q.1- What is the difference between Exception and Error in java ?Exception and Error classes are both subclasses of the Throwable class. The Exception class is used for exceptional conditions that a user’s program should catch. The Error class defines exceptions that are not excepted to be caught by the user program.

Q.2- What is the difference between throw and throws ?
The keyword throw is used inside method body to invoke an exception and throws clause is used in method declaration (signature). In other words Throws clause in used to declare an exception and thow keyword is used to throw an exception explicitly.

Q.3- How many types of errors?
The types of errors in java are
 1. Syntax Error : Syntax errors are also called as compiler errors. 
Example: Missing of semicolon, Mismatch in opening and closing parenthesis, Misspell a keyword etc.
 2. Run time/Logical Error: Run-time errors are errors that occur while your program runs.
Examples: Divide an integer by zero.
                   Using a null object to reference an objects members.
                   Storing a value that is of incompatible data type. etc.

Q.4- why we use try and catch block in java?
Try: The try block contains a block of program statements within which an exception might occur. A try block is always followed by a catch block, which handles the exception that occurs in associated try block. A try block must followed by a Catch block or Finally block or both.
Catch: A catch block must be associated with a try block. The corresponding catch block executes if an exception of a particular type occurs within the try block. For example if an arithmetic exception occurs in try block then the statements enclosed in catch block for arithmetic exception executes.

Q.5- What is the difference between difference between doGet() and doPost()?
doGet() and doPost() are HTTP requests handled by servlet classes.
In doGet(), the parameters are appended to the URL and sent along with the header information.
This does not happen in case of doPost().
In doPost(), the parameters are sent separately.
Since most of the web servers support only a limited amount of information to be attached to the headers, the size of this header should not exceed 1024 bytes.
doPost() does not have this constraint.
Usually programmers find it difficult to choose between doGet() and doPost().
doGet() shall be used when small amount of data and insensitive data like a query has to be sent as a request.
doPost() shall be used when comparatively large amount of sensitive data has to be sent.

Q.6- What is the difference between using getSession(true) and getSession(false) methods?
getSession(true) will check whether a session already exists for the user. If yes, it will return that session object else it will create a new session object and return it.
getSession(false) will check existence of session. If session exists, then it returns the reference of that session object, if not, this methods will return null.

Q.7- What is meant by a Web Application ?
A Web application is a dynamic extension of a Web or application server.
There are two types of web applications:   

• Presentation-oriented 
• Service-oriented. 

A presentation-oriented Web application generates interactive web pages, which contain various types of markup language and dynamic content in response to requests. On the other hand,
A service-oriented web application implements the endpoint of a web service. In general,
A Web application can be seen as a collection of servlets installed under a specific subset of the server’s URL namespace.

Q.8- How are the JSP requests handled ?
On the arrival of a JSP request, the browser first requests a page with a .jsp extension. Then, the Web server reads the request and using the JSP compiler, the Web server converts the JSP page into a servlet class. Notice that the JSP file is compiled only on the first request of the page, or if the JSP file has changed.The generated servlet class is invoked, in order to handle the browser’s request. Once the execution of the request is over, the servlet sends a response back to the client.