Java Notes by C. Sreedhar, GPREC

Java Programming (JP)
Lecture Notes

Unit 1
 Introduction:
◦ Over view of java, Java Buzzwords
◦ Data types, Variables and arrays, Operators
 Control statements,
 Classes and objects.
 I/O: I/O Basics, Reading Console input,
 writing Console output, Reading and
Writing Files.
 Inheritance: Basic concepts, uses super,
method overriding, dynamic method
dispatch,
 Abstract class, using final, the object class.

Unit 2
 String Handling:
◦ String Constructors, Special String
Operations-String Literals, String
Concatenation, Character Extraction, String
Comparisons. Searching Strings,
Modifying a string.
 String Buffer:
◦ String Buffer Constructors, length(),
capacity(), set Length(),Character
Extraction methods,
append(),insert(),reverse(),delete(),replace(

Unit 3
 Packages and Interfaces:
 Packages, Access protection,
Importing packages, Interfaces.
 Exception Handling:
◦ Fundamentals, Types of Exception,
◦ Usage of try, catch, throw throws
◦ finally, built in Exceptions.

Unit 4
 Multithreading:
◦ Concepts of multithreading, Main thread,
creating thread and multiple threads,
 Using isAlive() and join( ),
 Thread Priorities, synchronization,
 Interthread communication.

Unit 5
 Applets:
◦ Applet basics and Applet class.
 Event Handling:
◦ Basic concepts, Event classes, Sources
of events, Event listener Interfaces,
 Handling mouse and keyboard events,
 Adapter classes.
 Abstract Window Toolkit (AWT)
◦ AWT classes, AWT Controls.

Unit 6
 Java Swings & JDBC:
◦ Introduction to Swing: JApplet,
TextFields, Buttons, Combo Boxes,
Tabbed Panes.
 JDBC: Introduction to JDBC

Books
 TEXT BOOKS:
◦ Herbert Schildt [2008], [5th Edition], The
Complete Reference Java2, TATA
McGraw-Hill.(1,2,3,4,5,6 Units).
 REFERENCE BOOKS:
◦ Bruce Eckel [2008], [2nd Edition],
Thinking in Java, Pearson Education.
◦ H.M Dietel and P.J Dietel [2008], [6th
Edition], Java How to Program, Pearson
Ed.
◦ E. Balagurusamy, Programming with
Java: A primer, III Edition, Tata McGraw-
Hill, 2007.

List of Lab Experiments
1. Implementing classes and Constructors concepts.
2. Program to implement Inheritance.
3. Program for Operations on Strings.
4. Program to design Packages.
5. Program to implement Interfaces.
6. Program to handle various types of exceptions.
7. Program to create Multithreading by extending
Thread class.
8. Program to create Multithreading by implementing
Runnable interface.
9. Program for Applets.
10. Program for Mouse Event Handling.
11. Program to implement Key Event Handling
12. Program to implement AWT Controls.

Java Programming Examples
 Program to print some text onto output
screen.
 Program to accept values from user

Java Program: Example 1
public class firstex
{
public static void main(String []args)
{
System.out.println(“Java welcomes CSE
4A");
}
}

Dissection of Java Program
 public : It is an Access Modifier, which
defines who can access this method.
Public means that this method will be
accessible to any class(If other class
can access this class.).
 Access Modifier :
◦ default
◦ private
◦ public
◦ protected
{
{
4A");
}
}

 class - A class can be defined as a
template/blue print that describes the
behaviors/states that object of its type
support.
 static : Keyword which identifies the
class related this. It means that the
main() can be accessed without
creating the instance of Class.
{
{
4A");
}
}

 void: is a return type, here it does not
return any value.
 main: Name of the method. This
method name is searched by JVM as
starting point for an application.
 string args[ ]: The parameter is a
String array by name args. The string
array is used to access command-line
arguments. public class firstex
{
{
System.out.println(“Java welcomes CSE 4A");
}
}

 System:
◦ system class provides facilities such as
standard input, output and error streams.
 out:
◦ out is an object of PrintStream class defined
in System class
 println(“ “);
◦ println() is a method of PrintStream class
{
public static void main (String [ ] args)
{
System.out.println(“Java welcomes CSE 4A");
}
}

Possible
Errors
 class  Class
 firstex 
myex
{
public static void main (String [ ]
args)
 public 
private
{
args)
 static 
{
args)
{
system.out.println(“Java welcomes CSE
4A");
}
}
 system 
System
 out  Out
 println 
Println

Program to take input from
user
 Ways to accept input from user:
◦ Using InputStreamReader class
◦ Using Scanner class
◦ Using BufferedReader class
◦ Using Console class

Accept two numbers and display
sumimport java.io.*;
public class ex3
{
public static void main(String ar[ ])throws IOException {
InputStreamReader isr=new
InputStreamReader(System.in);
BufferedReader br=new BufferedReader(isr);
System.out.println("Enter first value");
String s1=br.readLine();
System.out.println("Enter Second value");
String s2=br.readLine();
int a=Integer.parseInt(s1);
int b=Integer.parseInt(s2);
System.out.println("Addition = "+(a+b));
}
}
The Java.io.InputStreamReader class is a bridge from byte
streams to character streams.It reads bytes and decodes
them into characters using a specified charset.
The Java.io.BufferedReader class reads text from a
character-input stream, buffering characters so as to provide
for the efficient reading of characters, arrays, and lines.

Using Scanner Class
import java.util.*;
public class ex4 {
public static void main(String ar[]) {
Scanner scan=new
Scanner(System.in);
System.out.println("Enter first value");
int a=scan.nextInt();
System.out.println("Enter Second
value");
int b=scan.nextInt();
System.out.println("Addition =
"+(a+b));
}
}
The java.util.Scanner class is a simple text scanner which
can parse primitive types and strings using regular
expressions.

Using Console
import java.io.*;
class consoleex
{
public static void main(String args[])
{
Console c=System.console();
System.out.println("Enter your name: ");
String n=c.readLine();
System.out.println("Enter password: ");
char[ ] ch=c.readPassword();
String pass=String.valueOf(ch);//converting char array into string
System.out.println(“Hai Mr. "+n);
System.out.println(“Ur Password is: "+pass);
}
}

Using BufferedReader class
import java.io.*;
class ex2 {
public static void main(String[ ] args) {
BufferedReader in =
new BufferedReader(new InputStreamReader(System.in));
String name = “ “;
System.out.print(“Enter your name: ");
try {
name = in.readLine();
}
catch(Exception e) {
System.out.println("Caught an exception!");
}
System.out.println("Hello " + name + "!");
}
}

Programming Languages:
 Machine Language
 Assembly Language
 High level Language

Machine language:
• It is the lowest-level programming language.
• Machine languages are the only languages understood by computers.
For example, to add two numbers, you might write an instruction in
binary like this:
1101101010011010

Assembly Language
 It implements a symbolic representation of
the numeric machine codes and other
constants needed to program a particular
CPU architecture.
 Assembly Program to add two numbers:
name "add"
mov al, 5 ; bin=00000101b
mov bl, 10 ; hex=0ah or bin=00001010b
add bl, al ; 5 + 10 = 15 (decimal) or
hex=0fh or
bin=00001111b
 MASM
 TASM

…
ADDF3 R1, R2, R3
…
Assembly Source File
Assembler …
1101101010011010
…
Machine Code File

Translation
 Interpreter
 Compiler

Compiler
 A compiler translates the entire source
code into a machine-code file
…
area = 5 * 5 * 3.1415;
...
High-level Source File
Compiler Executor
Output…
0101100011011100
1111100011000100
…
...
Machine-code File

Interpreter
 An interpreter reads one statement
from the source code, translates it to
the machine code or virtual machine
code, and then executes it.
…
area = 5 * 5 * 3.1415;
...
High-level Source File
Interpreter
Output

What is Java
 Java is a computer programming language that
is concurrent, object-oriented.
 It is intended to let application developers "write
once, run anywhere" (WORA), meaning that
code that runs on one platform does not need to
be recompiled to run on another.
 Java applications are typically compiled to
bytecode (class file) that can run on any Java
virtual machine (JVM) regardless of computer
architecture.
 Java is a general purpose programming
language.
 Java is the Internet programming language.

Usage of Java in Applets :
Example

Usage of Java in Mobile Phones
and PDA

Usage of Java in Self Test
Websites

Prerequisites to be known for
Java
 How to check whether java is present in
the system or not.
 How to install java in your machine.
 How to set path for java
 Check whether java is installed correctly
or not.
 What is JVM

Introduction to Java
 “B” led to “C”, “C” evolved into “C++” and
“C++ set the stage for Java.
 Java is a high level language like C, C++
and Visual Basic.
 Java is a programming language originally
developed by James Gosling at Sun
Microsystems (which has since merged into
Oracle Corporation) and released in 1995
as a core component of Sun Microsystems'
Java platform.
20 December 2015
C Sreedhar Java Programming Lecture Notes
2015 – 2016 IV Semester 37

 Java was conceived by
◦ James Gosling,
◦ Patrick Naughton,
◦ Chris Warth,
◦ Ed Frank and
◦ Mike Sheridan at Sun Microsystems, Inc in
1991.
 It took 18 months to develop the first
working version.
 Initially called “Oak”,a tree; “Green”;
renamed as “Java”, cofee in 1995.
 The language derives much of its syntax
from C and C++.
20 December 2015 38

 Motivation and Objective of Java: “Need
for a platform-independent (architecture-
neutral) language.
 Java applications are typically compiled
to bytecode (class file) that can run on
any Java virtual machine (JVM)
regardless of computer architecture.
 Java was originally designed for
interactive television, but it was too
advanced for the digital cable television
industry at the time.
 To create a software which can be
embedded in various consumer electronic
20 December 2015 39

Bytecode
 The output of Java compiler is NOT
executable code, rather it is called as
bytecode.
 Bytecode is a highly optimized set of
instructions designed to be executed
by the Java run-time system, called as
Java Virtual Machine (JVM).
 JVM is an interpreter for bytecode.
20 December 2015 40

Characteristics of Java /
Buzzwords Java Is Simple
 Java Is Object-Oriented
 Java Is Distributed
 Java Is Interpreted
 Java Is Robust
 Java Is Secure
 Java Is Architecture-Neutral
 Java Is Portable
 Java's Performance
 Java Is Multithreaded
 Java Is Dynamic
20 December 2015 43

Characteristics of Java
 Java Is Simple
 Java Is Robust
 Java Is Secure
 Java Is Architecture-
Neutral
 Java Is Dynamic
20 December 2015 44
Java is partially modeled
on C++, but greatly
simplified and improved.
Some people refer to
Java as "C++--" because
it is like C++ but with
more functionality and
fewer negative aspects.

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 45
Java is inherently object-oriented.
Although many object-oriented
languages began strictly as
procedural languages, Java was
designed from the start to be
object-oriented. Object-oriented
programming (OOP) is a popular
programming approach that is
replacing traditional procedural
programming techniques.
One of the central issues in
software development is how to
reuse code. Object-oriented
programming provides great
flexibility, modularity, clarity, and
reusability through encapsulation,
inheritance, and polymorphism.

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 46
Distributed computing involves
several computers working
together on a network. Java is
designed to make distributed
computing easy. Since
networking capability is
inherently integrated into Java,
writing network programs is like
sending and receiving data to
and from a file.

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 47
You need an interpreter to run
Java programs. The programs
are compiled into the Java
Virtual Machine code called
bytecode. The bytecode is
machine-independent and can
run on any machine that has a
Java interpreter, which is part of
the Java Virtual Machine (JVM).

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 48
Java compilers can detect many
problems that would first show up
at execution time in other
languages.
Java has eliminated certain types
of error-prone programming
constructs found in other
languages.
Java has a runtime exception-
handling feature to provide
programming support for
robustness.

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 49
Java implements several security
mechanisms to protect your system
against harm caused by stray
programs.

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 50
Write once, run anywhere
With a Java Virtual Machine
(JVM), you can write one
program that will run on any
platform.

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 51
Because Java is architecture
neutral, Java programs are
portable. They can be run on any
platform without being
recompiled.

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 52
Java’s performance Because
Java is architecture neutral,
Java programs are portable.
They can be run on any
platform without being
recompiled.

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 53
Multithread programming is
smoothly integrated in Java,
whereas in other languages you
have to call procedures specific to
the operating system to enable
multithreading.

 Java Is Simple
 Java Is Robust
 Java Is Secure
Neutral
 Java Is Dynamic
20 December 2015 54
Java was designed to adapt to an
evolving environment. New code
can be loaded on the fly without
recompilation. There is no need for
developers to create, and for users
to install, major new software
versions. New features can be
incorporated transparently as
needed.

Lab Program
 write a java program to display total
marks of 5 students using student
class. Given the following attributes:
Regno(int), Name(string), Marks in
subjects(Integer Array), Total (int).

Expected Output
Enter the no. of students: 2
Enter the Reg.No: 1234
Enter the Name: name
Enter the Mark1: 88
Enter the Mark2: 99
Enter the Mark3: 89
Enter the Reg.No: 432
Enter the Name: name
Enter the Mark1: 67
Enter the Mark2: 68
Enter the Mark3: 98
Mark List
*********
RegNo Name Mark1 Mark2 Mark3 Total
1234 name 88 99 89 276
432 name 67 68 98 233

Outline of the Program
class Student
{
// Variable declarations
void readinput() throws IOException
{
// Use BufferedReader class to accept input from keyboard
}
void display()
{
}
}
class Mark
{
public static void main(String args[]) throws IOException
{
// body of main method
}
}

import java.io.*;
class Student
{
int regno,total;
String name;
int mark[ ]=new int[3];
void readinput() throws IOException
{
BufferedReader din=new BufferedReader(new InputStreamReader(System.in));
System.out.print("nEnter the Reg.No: ");
regno=Integer.parseInt(din.readLine());
System.out.print("Enter the Name: ");
name=din.readLine();
System.out.print("Enter the Mark1: ");
mark[0]=Integer.parseInt(din.readLine());
total=mark[0]+mark[1]+mark[2];
}

void display()
{
System.out.println(regno+"t"+name+"tt"+mark[0]+"t"+mark[1]+"t"+mark[2]+"t"+total);
}
}
class Mark
{
public static void main(String args[]) throws IOException
{
int size;
BufferedReader din=new BufferedReader(new InputStreamReader(System.in));
System.out.print("Enter the no. of students: ");
size=Integer.parseInt(din.readLine());
Student s[]=new Student[size];
for(int i=0;i<size;i++)
{
s[i]=new Student();
s[i].readinput();
}
System.out.println("tttMark List");
System.out.println("ttt*********");
System.out.println("RegNotNamettMark1tMark2tMark3tTotal");
for(int i=0;i<size;i++)
s[i].display();
}
}

Lab Program: Complex number
Arithmetic
public class ComplexNumber
{
// declare variables
Default Constructor definition
{ }
Parameterized constructor definition
{
}
Use method getComplexValue() to display in
complex number form
{
}

public static String addition(ComplexNumber num1, ComplexNumber num2)
{
// Code for complex number addition
}
public static String subtraction(ComplexNumber num1, ComplexNumber num2)
{
// Code for complex number subtraction
}
public static String multiplication(ComplexNumber num1, ComplexNumber num2)
{
// Code for complex number multiplication
}
public static String multiplication(ComplexNumber num1, ComplexNumber num2)
{
// create objects and call to parameterized constructors
// call to respective methods
}

Lab Program: Complex number
Arithmeticimport java.io.*;
public class ComplexNumber
{
private int a;
private int b;
public ComplexNumber()
{ }
public ComplexNumber(int a, int b)
{
this.a =a;
this.b=b;
}
public String getComplexValue()
{
if(this.b < 0)
{
return a+""+b+"i";
}
else
{
return a+"+"+b+"i";
}
}

public static String addition(ComplexNumber
num1, ComplexNumber num2)
{
int a1= num1.a+num2.a;
int b1= num1.b+num2.b;
if(b1<0)
{
return a1+""+b1+"i";
}
else
{
return a1+"+"+b1+"i";
}
}

public static String substraction(ComplexNumber
num1, ComplexNumber num2)
{
int a1= num1.a-num2.a;
int b1= num1.b-num2.b;
if(b1<0){
return a1+""+b1+"i";
}
else
{
return a1+"+"+b1+"i";
}
}

public static String multiplication(ComplexNumber num1,
ComplexNumber num2)
{
int a1= num1.a*num2.a;
int b1= num1.b*num2.b;
int vi1 = num1.a * num2.b;
int vi2 = num2.a * num1.b;
int vi;
vi=vi1+vi2;
if(vi<0)
{
return a1-b1+""+vi+"i";
}
else
{
return a1-b1+"+"+vi+"i";
}
}

public static void main(String args[])
{
ComplexNumber com1 = new
ComplexNumber(2,4);
ComplexNumber com2 = new
ComplexNumber(6,8);
System.out.println(com1.getComplexValue());
System.out.println(com2.getComplexValue());
System.out.println("Addition of both Complex
Numbers are
:"+ComplexNumber.addition(com1,com2));
System.out.println("Substraction of both Complex
Numbers are
:"+ComplexNumber.substraction(com1,com2));
System.out.println("Multiplication of both Complex
Numbers are
:"+ComplexNumber.multiplication(com1,com2));
}
}

Java Notes by C. Sreedhar, GPREC

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