Preview:
Citation preview
- 1. Java Programming Language Md. Saifur Rahman Java Programming
Basic Concept
- 2. 1 Java TABLE OF CONTENTS Chapter Search Topic CHAPTER 1
.............................................................................
# SECTION 1.1
...........................................................................................#
Subsection 1.1.a
...............................................................................#
Subsection 1.1.b
...............................................................................#
Subsection
1.1.c................................................................................#
SECTION 1.2
...........................................................................................#
SECTION 1.3
...........................................................................................#
CHAPTER 2
.............................................................................
# SECTION 2.1
...........................................................................................#
SECTION 2.2
...........................................................................................#
Subsection 2.2.a
...............................................................................#
Subsection 2.2.b
...............................................................................#
Subsection
2.2.c................................................................................#
SECTION 2.3
...........................................................................................#
CHAPTER 3
.............................................................................
# SECTION 3.1
...........................................................................................#
SECTION 3.2
...........................................................................................#
SECTION 3.3
...........................................................................................#
Subsection 3.3.a
...............................................................................#
Subsection 3.3.b
...............................................................................#
Subsection
3.3.c.....................................................................................#
CHAPTER 3
.............................................................................
# SECTION 3.1
...........................................................................................#
SECTION 3.2
...........................................................................................#
SECTION 3.3
...........................................................................................#
Subsection 3.3.a
...............................................................................#
Subsection 3.3.b
...............................................................................#
Subsection
3.3.c.....................................................................................#
CHAPTER 3
.............................................................................
# SECTION 3.1
...........................................................................................#
SECTION 3.2
...........................................................................................#
SECTION 3.3
...........................................................................................#
Subsection 3.3.a
...............................................................................#
Subsection 3.3.b
...............................................................................#
Subsection
3.3.c.....................................................................................#
UseCtrl+F STRING TOPIC Complex programs FILE I/O TOPIC THREAD TOPIC
CLASS TOPIC INHERITANCE TOPIC CONSTRUCTOR TOPIC OBJECTTOPIC
METHODTOPIC POLYMORPHISM TOPIC EXCEPTION TOPIC ENCAPSULATION TOPIC
PACKAGES, INHERITANCEANDINTERFACES TOOPIC STATIC KEYWORDTOPIC
ABSTRACT KEYWORD TOPIC Link Web resource tutorials
http://www.c4learn.com/javaprogramming/
http://www.programmingsimplified.com/java/source-code/java-
hello-world-program http://www.similarsites.com/site/c4learn.com
http://docs.oracle.com/javase/tutorial/java/
http://beginnersbook.com/2013/05/method-overloading/
http://www.tutorialspoint.com/java/
http://www.javatpoint.com/static-keyword-in-java
http://guru99.com/java-tutorial.html
http://crunchify.com/java-tips-never-make-an-instance-fields-of-class-public/
Background colors RGB Color code Color sample RGB Color code Color
sample 234, 224, 215 200, 213, 204 209, 187, 211 213, 241, 179 172,
185, 202 190, 225, 192 199, 208, 219 227, 215, 229 208, 208, 207
191, 222, 198 6+
- 3. 2 198, 198, 197 214, 199, 174 204, 192, 174 234, 220, 197
237, 203, 200 221, 206, 184 192, 204, 172 205, 193, 183 172, 182,
170 197, 213, 205 226, 239, 217 235, 239, 255 245, 245, 220 210,
210, 210 233, 233, 233 233, 234, 234 211, 211, 211 255, 251, 230
225, 230, 246 210, 225, 240 220, 225, 237 237, 237, 237 227, 204,
233 208, 216, 222 233, 226, 171 242, 236, 185 175, 201, 194 253,
248, 212 234, 217, 154 196, 207, 187 250, 224, 206 Importance of
topics
- 4. 3 *** Most important ** Less important * important
Introduction to Computers and Java The smallest data item in a
computer can assume the value 0 or the value 1. Such a data item is
called a bit characters are composed of bits. characters that are
composed of two bytes fields are composed of characters or bytes. A
field is a group of characters or bytes that conveys meaning.
Compiling a Java Program into Bytecodes
- 5. 4 To compile javac Welcome.java To execute java Welcome
Things We need to know The three types of languages discussed in
the chapter are machine languages, assembly languages, high-level
languages. The programs that translate high-level language programs
into machine language are called compilers Android is a smartphone
operating system based on the Linux kernel and Java. Ashiq sir in
class main concepts Lecture 1 1. Lecture 2
- 6. 5 (9/29/2014) tools NetBeans ide 8.1 link
https://netbeans.org/downloads/ books java the complete reference
9th edition herbert schildt Filecreate File > new Project>
java > java Application > projectname + projectlocation >
finish Javaprogramworks Few littleconcepts 1. Function = method 2.
Add = class name (With starting capital letter) 3. add() = Method
(With starting lower case) 4. In java main() is not mandatory but
not execute 5. In business wecan give class file not sourcefile but
class file can convertinto Sourcecode C Java include import Object
1. Object = set of attributes = like structure OOP must have3
things 1. Encapsulation ( ) 2. Polymorphism( ) 3. Inheritance( )
Class 1. Domain 2. Idea 3. Environment 4. For object we need an
environment thats why we use class Suppose messi is the best
player. But he cannot play in banani park. He must need an good
field or environment where he can play football. Messi = object
Environment = class 5. User defined data-type 6. Set of objects
Fruit is a class then object = (mango , jackfruit, banana, etc)
Declaration class className { member variable declaration; member
fuction defination; } Classnaming conventions/rules 1. Name starts
with a uppercase 2. Main class name = file name First program
package class2; import java.io.*; class Class2 { public static void
main(String args[]) { System.out.println("Hello world"); } }
package class2; import java.io.*; public class Method_overloading1
{ public static void main(String args[]) { int num = 7; if(num % 2
== 0) { System.out.println("Even"); } else {
System.out.println("Odd"); } 1. program begins with a call to
main() method. 2. In main( ), there is only one parameter, albeit a
complicated one. String args[ ] declares a parameter named args,
which is an array of instances of the class String. (Arrays are
collections of similar objects.) 3. Output is actually accomplished
by the built-in println( ) method & displays the string which
is passed to it. & println( ) can be used to display other
types of information, too. The line begins with System.out, System
is a predefined class that provides access to the system, and out
is the output stream that is connected to the console. 4. All
statements in Java end with a semicolon. 5. Class Member Member
Variable Member Function
- 7. 6 } } Programprocess 1. Comments // This is a single line
comment /* This is a Multiline comment */ Lecture 3 (Wednesday,
October 01, 2014) packageclass3; import java.util.Scanner; public
class Input { public static void main(String args[]) {
System.out.print("Enterta number to check odd/even = "); Scanner sc
= new Scanner(System.in); int input = sc.nextInt(); if(input %2 ==
0) { System.out.println(input+" is even..."); } else
System.out.println(input+" is odd "); } } Function calling Wrong
Process packageclass3; import java.util.Scanner; public class
OddEvenCheckWithFuncCall { int oddeven(int input) { if(input %2 ==
0) { System.out.println(input+" is even..."); } else
System.out.println(input+" is odd "); Process one packageclass3;
import java.util.Scanner; class OddEvenCheck { int oddeven(int
input) { if(input %2 == 0) { System.out.println(input+" is
even..."); } else System.out.println(input+" is odd "); return 0; }
Process two packageclass3; import java.util.Scanner; class
OddEvenCheck { int oddeven(int input) { if(input %2 == 0) return 1;
else return 0; } } public class OddEvenCheckWithFuncCall Output Low
Run Execute Interprete Starts from main() High 1. Compile 2.
Convert machine code to electric signal
- 8. 7 return 0; } public static void main(String args[]) {
System.out.print("Enterta number to check odd/even = "); Scanner sc
= new Scanner(System.in); int input = sc.nextInt(); oddeven(input);
non-static method oddeven(int) cannot be referenced from a static
context so this cannot run in java but c can compile it } } }
public class OddEvenCheckWithFuncCall { public static void
main(String args[]) { System.out.print("Enterta number to check
odd/even = "); Scanner sc = new Scanner(System.in); int input =
sc.nextInt(); OddEvenCheck oec = new OddEvenCheck();
oec.oddeven(input); } } { public static void main(String args[]) {
System.out.print("Enterta number to check odd/even = "); Scanner sc
= new Scanner(System.in); int input = sc.nextInt(); OddEvenCheck
oec = new OddEvenCheck(); int out = oec.oddeven(input); if(out ==
1) System.out.println(input+" is even number"); else
System.out.println(input+" is odd number"); } } Introduction to
Java Applications { = an opening left brace } = the closing right
brace C T
- 9. 8 Complex programs packageclass3; import java.util.Scanner;
public class OddEvenCheckWithFuncCall { public static void
main(String args[]) { System.out.print("Enter a number to make a
pyramid = "); Scanner sc = new Scanner(System.in); int input =
sc.nextInt(); for(intr = 0; r0) { pos=pos+1; } else if(a[i] we
hired one person (guard), name getter. The responsibility of the
person was to provide exact duplicate copy of the cake. > we put
a lock on the class and gave the key to guard. so no one can
directly eat the cake, one has to ask getter for cake. Bingo !
problem solved ??, Not yet; there was another issue that happened -
I got the copy of cake and found that it was not sweet enough. I
added the sugar and asked the guard to replace this cake with
original one. Guard said - "that's not my duty". So we took another
step: > we hired one more person (guard), name setter. The
responsibility of the setter was to replace the original cake. I
gave the new cake, with enough sweetness, to setter and he replaced
it. Problem Solved ??, Not yet, one guy mixed the poison into cake
and asked the setter to replace it. So we were in problem again, so
we took anothe step, we gave addition responsbility to setter -
> Test the cake before replacing. Replace it if and only if it
passes certain test. OK !! This is the concept behined
ENCAPSULATION.In Technical terms - >Box act as Class >Cake
act as Field of the class >guards act as public methods of the
class >responsibilities of guards act as action performed by
methods So Encapsulation is the technique of making the fields in a
class private and providing access to the fields via public
methods. If a field is declared private, it cannot be accessed by
anyone outside the class, thereby hiding the fields within the
class. For this reason, encapsulation is also referred to as data
hiding. Medicine store example to explain Encapsulation: Lets say
you have to buy some medicines. You go to the medical store and ask
the chemist for the meds. Only the chemist has access to the
medicines in the store based on your prescription. The chemist
knows what medicines to give to you. This reduces the risk of you
taking any medicine that is not intended for you. In this example,
MEDICINES == Member Variables. CHEMIST == Member Methods. You ==
External Application or piece of Code. So, If Any external
Application has to access the Member Variables It has to call the
appropriate Member Methods which will do the task for it.(If You
have to access the Medicines You have to ask the Chemist). This way
the member variables are secure and encapsulated by a layer of
Member Methods. The Member Methods and Member Variables are bundled
together in to objects and can be accessed only by the objects. So
you need 2 steps if you have to access a public member of a class
you have to: 1. Create an object of the class 2. Then access the
member through object. You need 3 steps if you want to access the
private members of a class 1. You have to create an object of the
class 2. Then access the public method of the class through the
object 3. Then access the private member of the class through the
public method which has access to it. Also, encapsulation ensures
that you do not accidentally modify something else. i.e. if you
call the method setMy1stMemberVariable() it modifies only
my1stMemberVariable and does not changes my2ndMemberVariable i.e.
there are no side effects! Now refer to the above program and read
the comments. You should understand it properly.
- 32. 31 Packages, Inheritance And Interfaces Toopic No Term
Definition 1 Inheritance Inheritance is a process where one object
acquires the properties of another object 2 Subclass Class which
inherits the properties of another object is called assubclass 3
Superclass Class whose properties are inherited by subclass is
called assuperclass 4 Keywords Used extends and implements Finding
Packages and CLASSPATH -classpath option with java and javac to
specify the path to your classes inheritance public class Vehicle{
} public class FourWheeler extends Vehicle{ } public class
TwoWheeler extends Vehicle{ 1. Vehicle is the superclass of
TwoWheeler class. 2. Vehicle is the superclass of FourWheeler
class. 3. TwoWheeler and FourWheeler are sub classes of Vehicle
class. 4. WagonR is the subclass of both FourWheeler and Vehicle
classes. IS-A relationship of above example is - TwoWheeler IS-A
Vehicle FourWheeler IS-A Vehicle WagonR IS-A FourWheeler
- 33. 32 } public class WagonR extends FourWheeler{ } publicclass
Caller { publicstaticvoid main( String[] args ) { FourWheeler v1 =
new FourWheeler(); TwoWheeler v2 = new TwoWheeler(); WagonR v3 =
new WagonR(); System.out.println(v1instanceofVehicle);
System.out.println(v2instanceofVehicle);
System.out.println(v3instanceofVehicle);
System.out.println(v3instanceofFourWheeler); } } publicclass
Vehicle { } true true true true publicclass FourWheeler extends
Vehicle { } publicclass TwoWheeler extends Vehicle { } publicclass
WagonR extends FourWheeler { } Packages and Interfaces package
interfaces_2.pack1; importinterfaces_2.pack2.Balance;
publicclassCaller { publicstaticvoidmain(Stringargs[]) { Balance
obj[] =newBalance[3]; obj[0] = newBalance("Saifur",100); obj[1] =
newBalance("hasan",5000); obj[2] = newBalance("sazzad",100000);
//obj[0].show(); //obj[1].show(); //obj[2].show(); for(inti = 0;i
b) = "+ (a > b)); boolean c = (a < b); System.out.println("c
= (a < b) = "+ c); } } Char class ex1 { public static void
main(String args[]) { char ch1 = 'A', ch2 = 65;
System.out.println("ch1 = "+ ch1); System.out.println("ch1 = "+
ch2); } } Int Integer Data Type : 1. Integer Data Type is used to
store integer value. 2. Integer Data Type is Primitive Data Type in
Java Programming Language. 3. Integer Data Type have respective
Wrapper Class Integer. 4. Integer Data Type is able to store both
unsigned ans signed integer values so Java opted signed, unsigned
concept of C/C++. Class IntDemo { public static void main(String
args[]) { int number=0; System.out.println("Total Number : " +
number); } } Explanation : 1. Primitive Variable can be declared
using int keyword. 2. Though Integer contain default Initial Value
as 0 , still we have assign 0 to show assignment in Java. 3. +
operator is used to concatenate 2 strings. 4. Integer is converted
into String internally and then two strings are concatenated. Float
class ex1 { public static void main(String args[]) { float a =
3.1415F, b = 5.3432923423f; System.out.println("a = "+ a);
System.out.println("b = "+ b); } } Double class ex1 { public static
void main(String args[]) { double a = 3.1415, b = 5.3432923423;
System.out.println("a = "+ a); System.out.println("b = "+ b); } }
Double & Float class ex1 { public static void main(String
args[]) { float a = 9E5f; double b = 9E5; System.out.println("a =
"+ a); System.out.println("b = "+ b); } } Type conversion &
cast operation class ex1 { public static void main(String args[]) {
int a = 14; float b = 3.1413424f; int c = a % (int)b ;
System.out.println("c = "+ c); }
- 57. 56 } Variable Input/Output import java.io.*; class ex1 {
public static void main(String args[]) { DataInputStream in = new
DataInputStream(System.in); char ch; try{ System.out.print("Enter a
character : "); ch = (char) System.in.read();
System.out.println("You have entered : "+ ch); } catch (Exception
e){} } } import java.io.*; class ex1{ public static void
main(String[] args){ try{ InputStreamReader IN = new
InputStreamReader(System.in); BufferedReader BR = new
BufferedReader(IN); String s = BR.readLine();
System.out.println(s); } catch(Exception E){} } } import java.io.*;
class ex1{ public static void main(String[] args){ try{
InputStreamReader IN = new InputStreamReader(System.in);
BufferedReader BR = new BufferedReader(IN); System.out.print("Enter
Your age : "); String s = BR.readLine(); int age =
Integer.parseInt(s); System.out.println("Your age is : " + age); }
catch(Exception E){} } } Type conversion String s = BR.readLine();
int age = Integer.parseInt(s); String s = BR.readLine(); float age
= Float.parseFloat(s); Chapter 2 (Variables & Data Types)
- 58. 57 Chapter 3 (Control Statements) switch() import
java.io.BufferedReader; import java.io.InputStreamReader; class
ex1{ public static void main(String[] args){ try{ InputStreamReader
IN = new InputStreamReader(System.in); BufferedReader BR = new
BufferedReader(IN); System.out.print("Enter your academic year :
"); String s = BR.readLine(); int year = Integer.parseInt(s);
switch(year){ case 1: System.out.println("This is first year");
break; case 2: System.out.println("This is Second year");
- 59. 58 break; case 3: System.out.println("This is third year");
break; case 4: System.out.println("This is fourth year"); break;
default: System.out.println("You didn't entered Right year"); } }
catch (Exception E){} } } Loop Fibonacci series import
java.io.BufferedReader; import java.io.InputStreamReader; class
ex1{ public static void main(String[] args){ try{ InputStreamReader
IN = new InputStreamReader(System.in); BufferedReader BR = new
BufferedReader(IN); System.out.print("Enter your how many fibonacci
numbers : "); String s = BR.readLine(); int input =
Integer.parseInt(s); int f0 = 0, f1 = 1, f2; for (int i = 0; i
- 60. 59 } Nested loop System.out.print("Enter number up to : ");
String s = BR.readLine(); int input = Integer.parseInt(s); int i,
j; for (i = 1 ; i