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Rajeev Gupta [email protected]
What is software engineering
the major problem in SW development is communication ...
day-1
TOC
oops
api: multithreading, network programming, jdbc
misc : if time permit
introduction:
jdk: Developer need it
Why Object-Oriented?
jre: need to have an instance of jvm
jvm:virtual simulated os
java 1.6 vs java 6.0
J2SE, JEE, J2ME
J2SE: JAVA 2 STD EDITION, Core java
J2ME: java 2 micro edition
..mobile...
J2EE: ...enterprise edition,Web development
NOW 2 is droped...
JRE and JVM
jre=jvm+java api
jvm:
class loader
Byte code verifier
Exec Engine
GC
Security manager
JAVA=oops+api+jvm
platform=os+machine arch..
coding without analysis is crime
first do ooad* then do oops
i will go in depth depends on ur desire
dont run 2 if it is not there!!!
OOAD IS NOT IN TOC..WILL DISCUSS IF U NEED...AND ASK ME!!!
DEFINATION OF JAVA
java is
platform independent
architectureal nutral
secure
wora
compiled as well interpreted
multithreaded inbuild..
support network programming buityfully..
support applet
support distributed programming*
..
..
PROCEDURAL VS OOPS
PROCEDURAL :focus on algo ,data is secondary...data may be mismunpulated ,global data problem
ex C: king of all procedural language
u can do anything in C possibly may not in java
C is faster
C is powerful
then java or kava then why java???
C:king of all procedural language
C++: big massay language
Java: best programmer supportive oop language
C# duplicate of java optimized for win...:)
Procedural programming
if ..else : conditional
for ,while, do..while: iteration
operators: mathmatical ,logical etc
data type in java
Q: prime no checking
Q: divisibility by 11
Q: star questions
Array: one D, two D
call by value vs call by reference
notepad
edit +
ide: eclipse
Day 2
Object orientation
encapsulation
abstraction
polymorphism
inheritance
supportive concepts:
typing
persitance
message passing
Concept of class
object
reference
heap and stack
constructor
concept
this
Constructor chaining
inheritance
various type of inheritance
why not multiple inheritance
constructor and parameter passing from derived const to base const
what u have done
if else
for loop
disadv of procedural langages
data security
global data problem...
procedural langages is not fitting to real world problems...
have a break.....
need of function
****************************************
Welcome to java
****************************************
i love to
****************************************
****************************************
will cover
function
array
oops concepts today
function : a job is to be done
void printStar(int a)
OOPs
Object based programming language=oops-(run time polymorphism)
class: category
object : run time ex of class
a object is useless if it not communicate to other one!!!!!!-----------message passing
focus on essential things
abstraction
data hiding
message passing
encapsulation
inheritance
polymorphism
typing
persistance
etc....
i will run two if it is there....i belive it is there...
calculator program
add
substract
multiply
divide
primeChecker
if i need repeated set of data: i need array…………….continuous hectrogenus set of data
int x[]=new int[4];
Assignment:
Q1. Calculator
Q2. Find max min from a array
Q3. Find avg of an array
Q4. Short notes
gc
abstaction
inheritance
polymorphism
class
object
Stack vs heap
Q5. Procdural vs oops
Topics day3
static method
array of objects
constructor
this
inheritance...super
abstract class, interface and final class
final keyword: final variable !, final method, final class...
polymorphism
call by value vs call by reference
String
Wrapper class
if time permit:....
IO
Exception Handling
collection -ready made ds
and
multithreading: game programming, simulation, mobile ,server programming
Summary till now.....
array
int x[]={1,3,5,6}
for(int i=0;i<4;i++)
sop(x[i]);
heap vs stack
primitives: stack
object: heap
ref: stack
int x[]=new int[5];
Static method
a method declared static is ...
static method can only access static data..imp
u cant access non static data in a static context.........
most imp.....
class Demo
{
public static void main(String args[])
{
System.out.println("hi");
}
}
this:
to resolve confusion bw instance variable and local
constructor chaining: calling one const from other
this is implicit argument to every method call
ie when we call a method (any non static method)
java implicitly pass a ref to the object on which method is fired ..very imp concepts even u will find developer of 3 year exp are not aware....
recursion...if time permit
Demo()
{
Demo();
}
inheritance
Father
|
Son
stupid to use parent and child termonology
better to use Base class and Derived Class
NB: We cant write any class in java without inheritance
every class inherit a class called Object...
class A extends Object
{
}
class A {
}
are equivalent statements..having same sementics
how to pass value from derived const to base const...
son 1kg sweet
before eating myself my moral resp.. (in oops it is must)
to pass on portion of father ....
package com.oops1;
class A
{
int i;
int j;
public A(){}
public A(int i,int j)
{
super();
this.i=i;
this.j=j;
}
public void showA()
{
System.out.println("value of i:"+i);
System.out.println("value of j:"+j);
}
}
class B extends A
{
int k;
public B(){}
public B(int i,int j,int k)
{
super(i,j);
this.k=k;
}
public void showB()
{
showA();
System.out.println("value of k:"+k);
}
}
public class DemoInheritance {
public static void main(String[] args) {
B b=new B(23, 45, 78);
b.showB();
}
}
Q1. Simple question on constructior, cont chaining
Q2. Simple Question on inheritance
Single ,multiple ,multilevel, heri....
Q3. use of super
Q4. Array..array of object...try dog example...ie create a array of dog objects…
Q5. use of super
Q6 try R and D
................................................................................................................................................
final class
normal class
abstract class
interface
flexibility is very difficult to achieve u have to earn it...
The purpose of declaring a method final is to stop polymorphism comment on this?
//single line comment
/*
multiline comment
*/
/**
java doc
*/
@Override
annotation
to be discuss latter
interface :
B a=new B()
C c=new C();
We can assign base class pointer with the derived class object but reverse is not true....
child has more then father has!!!!
Day-4
Interface
Polymorphism
io
Exception handling
interface
multiple inheritance
global constant
call back*
support design to interface
IS-A: inheritance
Has-A
strong: like room in building
weak: a emp works in a company
Use-A
Practical ex of USE-A
a passanger use a car to reach from railway station to hotel
to understand user requrments…………..Analysis is imp
but………….Analysis Analysis Analysis leads to paralysis
coding: just a small part of sw deve...
OOA
find the domain model
find the classes or interfaces
OOD
find the realationship bw those classes or interfaces
Coding
then think about java...
testing
RAD
RUP: relational unified process
the most costly activity of sw development is maintance
interface A
{
int i;
}
i is in fact
public static and final==>global const
how to solve diamond problem: multiple inheritance
IO
decorator design pattern is the key concepts
ex:
BufferedReader br=new BufferedReader(new InputStreamReader
(System.in));
easy way :
Scanner class in java 1.5
magic of decorator design pattern
IO
console
File handling
Read and Write
File f=new File("c:\\raj.txt");
FileReader fr=new FileReader(f);
BufferedReader br=new BufferedReader(fr);
public class IODemo {
public static void main(String[] args) {
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String a=null;
try {
a=br.readLine();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(a);
}
slip bw cup and sip....
Exception handling
Checked
Unchecked: generally due to poor logic
Java cant help us...
All happen at run time
Ex of Unchecked
the problem cant be suggeted by compiler
logical problem of programmer java has nothing to do with that....
try
{
a=br.readLine();
}
catch(Exception ex)
{
ex.toString();
}
catch(IOException ex)
{
System.out.println(ex);
}
finally
{
System.out.println("i am here");
}
Latent errors
Business Analysist
|
|
|
System Analysist
this is difficult field .....
Equality of primitive vs Equality of objects
Equality of primitive
==
not wise to check for == in the case of two double or float
rather check for inEquality
2.0 2.0000 not a good thing to compare two double or float
2 2
Summary till now:
...................................................
Exception handling
...................................................
key words:
try: put risky code under observation
catch: possible remedies
throw: explicitly throwing exceptions, user defined exception
throws: throwing responsibilities our problem to someone else
finally: whether exception occur or not finally is going to be executed...
...................................................
we disucss about exception handling
collection
next day plan
:---------------------
visibility levels
multithreading
jdbc if time permit....
----------------------------------------------------------
Exception handling is not same as function calling!!!!!!!
try
{
tatement1
statement2--problem1
statement3
statement1
statement1
}
catch(Problelm1...)
{
sop("hi");
}
catch(Problelm2...)
{
}
catch(Problelm2...)
{
}
In the case of exception handling if exception occur at statement2 ..it would be handled by catch for problem1 and now control will not go back in the try block…
Q. if finally is going to execute always then why hell we are using it?
finally
{
sop("india");
}
sop("india");
fun()
{
statement1
fun2();
statement2
statement3
}
fun2()
{
...
...
}
- Type mismatch: cannot convert from boolean
to String
try {
br = new BufferedReader(new FileReader("c:\\raj\\abc1.txt"));
System.out.println("hi i am not going to printed");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
System.out.println("file not found");
}
How to learn an new technology
First have a concept then u must have POC (Proof of concepts) then only u can thought applying it to ur job
throw: explicitly throwing exceptions, user defined exception
user define exception
if balance is less then 1000 i want to throw an exception
Accouting sw
NotSufficientFundException
i am near reality
oops is nothing but our life....
class Account
{
int accNo;
int fund;
public void withdrawMoney(int money)throws
NotSufficientFundException
{
int temp=fund-money;
if(temp<=1000)
throw new NotSufficientFundException();
System.out.println("money is withdrawn");
fund=fund-money;
}
public Account(){}
public Account(int accNo, int fund) {
super();
this.accNo = accNo;
this.fund = fund;
}
public void showFund()
{
System.out.println("the current balance is:"+fund);
}
}
public class UserDefineEx {
public static void main(String[] args) {
Account ac=new Account(23434554,5999);
try {
ac.withdrawMoney(4000);
} catch (NotSufficientFundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
When to use try ..catch when to use throws/throw not a esay ans....
Design to interface
Separation of concern
imp topics:
arrray
Serious limitation of array
can’t grow at run time i.e. size is fixed
Removing and inserting and new element is not cup of tea...
collection
Readymade data structure.....
stack, queue,set, map etc
Q What is the diff between array and array list
array array list
size is fixed not fix...
finding is easy
removing and inserting dam easy
and new element is
not cup of tea...
fast slow
in core java: collection and multithreading is most imp topics for any serious interviewer
package called
java.util
Q. difference between collection, Collection, Collections…
collection:
name of topics
<<Collection>>
an base interface
Collections:
static utility class
There are various type of ds like
LinkedList, DoublyLinkedList, Tree, Stack, Queue, Forest, Graph, Heap, Map, Set
Java makes our life easy as it provided almost all the ds readymade to us...
What is the challenge of collection? There is many readymade ds ...where to use what
leftover : otherwise imp topics.....
Collection and Object class, comparable and comparator interface
topics :
jdbc
revision collection
collection
readymade datastructure
link list:
grow dynamically at run time
single-in one direction , doublely-both direction
tree:-
ArrayList: single
LinkedList: doubly l...list
hashing make program faster.....
program without generics and with generics
with generics
j d b c tm
Java Data base conn
Way to connect to db...
DBMS: SQL, PL/SQL
9i internet
10g grid computing
11app
grid computing is father of cloud computing…which is the future....video on utube.. …check out…
client===========server
java code db stored in oracle mysql etc
2-tier arch....
java gives specification and people follows it...
ie every vendor has its own implemention of driver..and related classes
they pack it into a formate that is called jar file
connector-j.jar for mysql
class123.jar for oracle
jdbc is subset of ODBC (Open dbc.. ms)
hibernate is some ORM(obejct relation mapping )used professionally for commercial projects......
database operation:-
DML: data manipulation language
DDL: data defination language
TCL: transaction control lang...
CURD
that u cant eat....
c: create
u:update
r: read
d: delete
package com.jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DemoConn {
public static void main(String[] args) {
Statement stmt=null;
ResultSet rs=null;
Connection con=null;
try
{
try
{
Class.forName("com.mysql.jdbc.Driver");
}catch(ClassNotFoundException ex){System.out.println("driver is not installed");}
con=DriverManager.getConnection("jdbc:mysql://localhost:3306/raj","root","root");
stmt=con.createStatement();
rs=stmt.executeQuery("select * from dept");
//rs is like a pointer
//till table not finish.. trevers it..process it..save it..
//jdbc in nutshell
while(rs.next())
{
System.out.println(rs.getInt("deptid"));
System.out.println(rs.getString("deptName"));
}
}
catch(SQLException ex)
{
System.out.println("no db");
}
//should always be executed....
finally
{
if(con !=null)
{
try
{
con.close();
}catch(Exception e){}
}
if(rs!=null)
{
try
{
rs.close();
}catch(Exception e){}
}
}
}
}
what is db programming
You are already aware of file handling file handling…
Db programming is sort of client server program…u should know IP address where server is running and port no ie tell about service we want to access…
What is the algo………….
open a connection
read the file till not end
that manipulte the records
finally close the connection..
ip port no.....
TCP/IP
ip: network layer
tcp: transport layer
first i have ip /port of server(ie db server)
name of bdase and usernane password
mySql : 127.0.0.1: 3306
root,root
name of dbase to be connection: raj
table to connected : emp
Statement
: for simple queries
PreparedStatement
:little faster and more flexible then Statement
Callable Statements:
Strored procedure.. sort of function on server side
futher references:--------------
jdbc tutorial on visualbuilder.com
roseindia jdbc tutorial u find good code...
-------------------------------------
End of the session
i hope u have enjoyed with me
and finally
Semantic is more imp then syntax....it depends...on which side of table u are....
