java - the fast way - the ultimate, quick and easy java programming guide [hq pdf][psycho.killer]

8/18/2019 Java - The Fast Way - The Ultimate, Quick and Easy Java Programming Guide [HQ PDF][Psycho.killer]

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Java

The Fast Way

The Ultimate, Quick and Easy

Java Programming Guide

Eng. Alexander Mosgov


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Chapter 1:

Data Typesva provides a rich set of data types. Every variable declared or defined has a particular data

e assigned data type specifies the size and the type of values that a variable can store.

ovides a number of data types which have their particular significant in deciding the approp

e by the programmer while programming.

ere are mainly two basic types of data types:

Primitive

Non- primitive

imitive data types

mitive data types are also known as built-In data types. These data types are predefined b

guage. Java provides the following primitive data types in Java :

te

8 bit signed integer

Rang e is -128 to 127

Used in arrays w

memory significantly matters.

Integer Data type are 32 bit signed integer

Minimum value is - 2,147,483,648.(-2^31) and Maximum value is 2,147,483,647

Default value is zero.

ort


Range -32,768 to 32,767

Used in larger arrays to save memory space

ng



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Minimum value is -9,223,372,036,854,775,808 and Maximum value

9,223,372,036,854,775,807

This data type is used if there is a need of higher range than Int.

Default value for Long data type is 0L

oat

Single precision 32bit IEEE 754 floating point.

Float is used to deal with larger array of floating point numbers to sav

memory.

Default value for Float data type is 0.0f.

ubleDouble precision 64 bit IEEE 754 floating point.

Default data type / choice for decimal values

Default value for Double data type is 0.0d.

olean

Boolean data types represent 1 bit information

There are only two possible values for Boolean data types i.e true and false

Boolean data types are mainly used in condition checking.

Default value for Boolean data type is false.

arSingle 16 bit Unicode Character

Range is '\u0000' - '\uffff'

Used to store a character

Range


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ta Type

Size Default Value

32-bit 0 -2,147,483,648 to 2,147,483,647

ort 16-bit 0 -32,768 to 32,767

ng 64-bit 0L -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

te 8-bit 0 -128 to 127

at 32-bit 0.0f 1.40129846432481707e-45 to 3.40282346638528860e+38

uble 64-bit 0.0d 4.94065645841246544e-324d to

1.79769313486231570e+308d

ar 16-bit '\u0000' 0 to 65,535

olean 1-bit False True or False only

on-Primitive data types

n-primitive data types are not predefined data type in any programming language. They are cr

the programmer for their use and efficiency of a program. These variables are also know

erence variables.

n-primitive data types in Java include Arrays, Interfaces and class.


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Chapter 2:

Operators and Expressionsva is a very rich language in terms of operators it has. Java operators can be classified int

lowing categories:

Arithmetic Operator Relational operator

Logical operator

Assignment operator

Increment-decrement operator

Conditional operator

Bitwise operator

Other special operators

rithmetic operators

ese operators are used in constructing mathematical expressions. Java provides all the com

thmetic operators used algebra including +,-,/,*,% . All these operators have the

nctionalities as in other languages.

perator Meaning

Unary plus or addition operator

Unary minus or subtractionoperator

Division operator

Multiplication

Modulo Division (Remainder

Operator)

me example of arithmetic operators are as shown below:

q P-q p*q p/q p%q -p/q

the above given examples, p and q are known as operands and these p and q can be variab

nstants.

eger arithmetic

hen all the operands in the expression are integers then the expression is known as in

pression and the operations in this expression are known as integer arithmetic. The output

eger arithmetic is always an integer value. For the above given example in Arithmetic opera


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we take p=14 and q=4,

+ q=18

q =10

q= 56

q = 3

% q=2

l the results are very easy to understand except / and %.

we know an integer expression results in an integer, therefore results of p/q is 3 where de

rt is truncated. Also modulo operator results in remainder thus provides 2 as result.

case of Modulo division operator , the sign assigned to result is the sign of the first operan

vidend.

%4 =2

%-4=2

8%4=-2

8%-4= -2

al Arithmetic

real arithmetic involves real operands. In real arithmetic, operands are either in expontation or decimal notation. As we know, in floating point, values are rounded-off to the perm

mbers of digits.

xed Mode arithmetic

expression having operands of both types as integers and real is known as mixed mode arith

pression. If one operand is real and other is integer then the integer operator is itself convert

l and after conversion, real arithmetic is performed.

. 25/10.0= 2.5 whereas 25/10 produces 2.

elational Operator

hen there is a need to compare two quantities, relational operators are used. An expression

q or p>=30 having a relational is known as relational expression. The output of a relat

pression is either TRUE or FALSE. There are 6 relational operators in Java which are given i


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lowing table.

perator Meaning

= Is equal to

= Not equal to

Less than

= Less than or equal to

Greater than

= Greater than or equal to

ample to demonstrate the relational operators:

blic class Test {

blic static void main(String args[]) {

int p = 10;

int q = 20;

System. out. println ("p == q = " + (p == q) );

System.out.println ("p != q = " + (p != q) );

System.out.println ("p > q = " + (p > q) );

System.out.println ("p < q = " + (p < q) );

System.out.println ("q >= p = " + (q >= p) );

System.out.println ("q


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ntrol in a program.

ogical Operators

ere are three logical operators in Java. These operators are logical AND, logical OR and lo

OT. The logical operators logical AND ,logical OR are used when there is a need to fo

mpound condition with a combination of two or more relational expressions.

perator Meaning and Description

&

This operator is known as Logical AND

operator. When both operand are true or

non-zero, then the condition is true

otherwise false

This operator is known as Logical OR

operator. When at least one operand is

true or non-zero, then the condition is true

otherwise false

This operator is known as Logical NOT

operator and Used to reverse the logical

state of any operand. If a condition is false

then this operator will make it true and if

true then it will make false.

signment Operator

signment operators come in existence when there is a need of assigning value of a spec

pression to a given variable.

tead of assignment operator, java also provides shorthand assignment operators with the follo

ntax:riable operator = expression;

e above expression is equivalent to variable=variable operator (expression)

orthand Assignment Operator

tatement with simple assignment

perator

Corresponding statements with

shorthand operator =p+1 P+=1


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=p-1 p-=1

=p*(n+1) P*=n+1

=p/(n+1) p/=n+1

=p%q P%=q

blic class Demo1

public static void main(String args[])

{

t value = 10;

System. out .println( "value is " +value);

// Shorthand assignment operators

int a1 = 4;

int a2 = 8;

a2 += a1;

System. out .println( "a1 is " +a1);


a1 = 4;

a2 = 8;

a2 -= a1;



a1 = 4;

a2 = 8;

a2 *= a1;



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System. out .println( "********** /= Assignment Operator*********" );

a1 = 4;

a2 = 8;

a2 /= a1;System. out .println( "a1 is " +a1);


a1 = 4;

a2 = 8;

a2 %= a1;



}

ue is 10

is 4

is 12

is 4

is 4

is 4

is 32

is 4

is 2

is 4

is 0

ncrement and Decrement Operator

va provides two very important operators i.e increment and decrement operators having synta


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d – respectively.

hese operators are specific types of assignment operators with following features

Unary operators working with a single operand.

Increment operator increases the value of the operator to which it is

applied by 1

Decrement operator decreases the value of the operator to which it is

applied by 1

here are two versions of these operators:

Preincrement and predecrement operator

Postincrement and postdecrement operator

e-increment operator

Preincrement operator “++” is applied to a Variable by writing it

before the variable’s name. Preincrement operator firstly increases the value of variable by 1 a

then that incremented value is used in that expression.

We can’t apply this operator with final variables or constants.

Pre- decrement Operator

Predecrement operator “--” is applied to a Variable by writing it

before the vatiable’s name. Predecrement operator firstly decreases the value of variable by 1

then that decremented value is used in that expression.


ost-increment operator

Postincrement operator “++” is applied to a Variable by writing it

the variable’s name. Postincremnt operator firstly use the same non-incremented value

that expression and after that increases that variable by 1.


ost- decrement Operator

Postdecrement operator “--” is applied to a Variable by writing it a

the vatiable’s name.


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Postdecrement operator firstly use the same non-decremented valu

that expression and after that decreases that variable by 1.


xample:

ass Increment {public static void main (String args[]) {

int p = 1;

int q = 2;

int r;

int s;

r = ++q;

s =p++;

r++;System.out.println(“p = “ + p);

System.out.println(“q= “ + q);

System.out.println(“r = “ + r);

System.out.println(“s = “ +s);

}

he output of this program follows:

p = 2

q = 3

r= 4

s = 1

you are well understood with the above program,, then you please try decremenerator yourself. It works in the same way as increment with a single difference t

decreases value by 1 instead of increasing.

onditional Operatorrnary operator is a very important conditional operator provided by Java. It has the conditiona

tements of following form:

pression 1 ? expression 2 : expression 3


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the above conditional statement, firstly expression 1 is calculated and the result of the conditio

pression depends on its result whether it is true or false.

expression 1 is true then expression 2 is evaluated and it becomes the resultant or final value o

ove given conditional statement.

expression 1 is false then expression 3 is evaluated and it becomes the resultant or final value

above given conditional statement. Always remember, only one of the both expression 2 and

pression 3 is calculated depending of expression1’s result.

= 10;

= 15;

( p > q ) ? p : q ;

the above given example, r is assigned the same value as q.

is operator behaves same as if-else. Above program in if-else

p>q)

r=p;

eq;

itwise operators

va provides a rich set of bitwise operators which operate on individual bits of an integer. In c

erand is shorter than int then before applying bitwise operations that is converted into int. The

erators can’t be applied to double or float.

stly an integer is represented in binary form and after that bitwise operators are applied on the

dividual bits of the binary forms of the corresponding operands. For example 6 is represented

nary as 110 . 2’s complement is used for storing negative numbers.

blic class Bitwise {

ublic static void main(String args[]) {

int p = 60; /* Binary representation 60 = 0011 1100 */int q = 13; /* Binary representation 13 = 0000 1101 */

int r = 0;

r = p & q; /* Binary representation 12 = 0000 1100 */

System.out.println("p & q = " + r );

r = p | q; /* Binary representation 61 = 0011 1101 */

System.out.println("p | q = " + r );

r = p ^ q; /* Binary representation 49 = 0011 0001 */


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System.out.println("p ^ q = " + r );

r = ~p; /* Binary representation -61 = 1100 0011 */

System.out.println("~p = " + r );

r = p > 2; /* Binary representation 15 = 1111 */System.out.println("p >> 2 = " + r );

r = p >>> 2; /* Binary representation 15 = 0000 1111 */

System.out.println("p >>> 2 = " + r );

is would produce the following result:

& q = 12

q = 61q = 49

= -61

> 15

>>> 15

perators Precedence and Associativityery operator has a precedence and associativity associated with it. Precedence of operators is

determining the sequence of operators for evaluating an expression in case expression has a

mber of operators. In an expression, the operators having higher precedence are evaluated firs

sociativity is the concept for determining the evaluation order of operators when there are mu

erators with same precedence then associative determines either to be evaluated from left to ri

right to left.

ecedence withRank

Operator Type Associativity

1

()

[]

·

Parentheses

Array subscript

Member selection

Left to Right

2++

--

Unary post-increment

Unary post-decrementRight to left

++

--

Unary pre-increment

Unary pre-decrementUnary plus


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3+

-

!

~

( type )

Unary minus

Unary logical negation

Unary bitwise

complement

Unary type cast

Right to left

4

*

/

%

Multiplication

Division

Modulus

Left to right

5+-

AdditionSubtraction

Left to right

6

>

>>>

Bitwise left shift

Bitwise right shift with

sign extension

Bitwise right shift with

zero extension

Left to right

7

<

>=

instanceof

Relational less than

Relational less than or equal

Relational greater than

Relational greater than

or equal

Type comparison

(objects only)

Left to right

8==

!=

Relational is equal to

Relational is not equal

to

Left to right

9 & Bitwise AND Left to right

10 ^ Bitwise exclusive OR Left to right

11 | Bitwise inclusive OR Left to right

12 && Logical AND Left to right

13 || Logical OR Left to right

14 ? : Ternary conditional Right to left

15

=

+=

-=

*=

/=

%=

AssignmentAddition assignment

Subtraction assignment

Multiplication

assignment

Division assignment

Modulus assignment

Right to left


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Chapter 3:

Decision Making Statements in Javametimes there is a need to take decisions on the basis of given condition. Based on the

nditions, it is the decided that which condition is satisfied and statements correspondi

at conditions is executed.

ere are mainly three types of decision making statements in Java

1. If statement

2. switch statement

3. conditional operator statement

statement is further implemented as

Simple if statement If-else statement

If-else Ladder

Nested if –else statement


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tatement

tatement is helpful in making a decision in our program.


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Simple if statement

he condition given in if is true then only the statements corresponding to that if block is execuntax of if statement

condition)

condition is true , these Statements written inside curly brackets will be executed .

ogram

public class ifstatement

{


{

int test1=10;

if (test1>10)

system.out.println(“you are wrong”);

if(test1>5)

{

System.out.println("good");

}

}

}

Result of this program is “good”.


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if else statement

case the if condition is true then the statements inside curly brackets of if block is execu

herwise statements of the else block are executed.

condition)

condition is true, these statements will be executed.

e

case the condition given in if statement is false , these statements will be executed.

se statements are executed always.

ogram

public class if-elsestatement

{


{

int test1=10;

if (test1>10)

{

system.out.println(“you are wrong”);}

else

{ System.out.println("good");

}

}

}


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Output

good


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if–else-if ladder

ntax with meaning

condition1)

atements // executed only if condition1 is true.}

e if (condition2)

atements // executed only if condition1 is true

e if (condition-n)

atements // execute only when condition-n is true}

e

atements // executes when all above given conditions are false.

atements // these statements are always executed.


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Nested if…else statement

hen there are a series of decision, then we have to use a number of if-else statements in nested

m.

condition1){

/Executes when the condition 1 is true

f( condition2){

//Executes when the condition 2 is true

blic class Test1 {

ublic static void main(String args[]){

int a = 30;

int b = 10;

if( a >10 ){

a== 30)

tem.out.println(” a is equal to 30”);

e

tem.out.println(“ a is not equal to 30”);

else System.out.print("a is less than 10");

}

}

}

tput : 30

he switch Statement

we studied, if statements are useful in deciding the sequence control of program. But in case re a number of alternatives to be tested against a variable, then the complexity of the program

umber of IF statements increase. Switch statements solves this problem by allowing a variabtested against a list of values. These values are called cases. When the variable is matched w

rticular case then the statements of that particular case is executed.

ntax:

witch (expression ){


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case value1 :

block1

break; //optional

case value2 :

block2

break; //optional

………………………………………..…………………………………………….

……………………………………………………

default : //Optional

//default block

les for switch statement

The switch statement can have a variable of type short,int,byte or char.

A Switch block can have any number of case statements with the following syntax

Case value :

any The value specified in case should be of same data type as variable in the switc

statement. Also this value must be any constant or literal.

When the variable of switch statement is matched with nay case value then the

statements following that case will be executed until Break statement is reached.

As the execurion reaches to a break statement, the switch terminates, and the execut

is transferred to the next line following the switch block.

Putting Break in each case is not necessary. In case no Break appears, the execution

through the subsequent given cases until a Break is executed or the switch terminates.

There may be an optional default case in a switch at the end of switch. Default case

executed when value of a variable is unmatched with all given cases.ample:

blic class Test1 {


char letter = 'S';

switch(letter)


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{

case 'P' :

System.out.println("Duffer");

break;

case 'Q' :

case 'S' :

System.out.println("Excellent");break;

case 'R' :

System.out.println("You failed");

Case 'F' :

System.out.println("try again");

break;

default :System.out.println("Invalid input");

}

tput:

cellent

oping statements in java

metimes there is a need to execute a block of statements several times depending on any condit

is type of situation is handled by Loops in java.

va allows these loops mechanisms with three types of loops:

for Loop

while Loop

do...while Loop

e for Loop

for loop is a control structure which executes the statements within this IF block several times


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pending on conditions.

for loop is beneficial when we already know for how many times to repeat a particular task.

ntax:

(initialization ; Boolean_expression ; update)

/body for the loop

quence of steps followed in a for loop:

First of all initialization statement is executed. This statement allows declaring or

initializing loop control variables.

Now the Boolean expression or test condition is evaluated. If this Boolean expressi

comes to true, the defined body of the for loop is executed. Otherwise in case of false, th

body does not execute and control is transferred to the statement following the for loop.

After once execution of body of loop, the control is transferred to the update stateme

which generally includes increment or decrement. This statement is generally used to upd

any loop variable.

Again there is a evaluation of Boolean expression. If it is evaluated true, the loop a

executes and this process (loop body , then update step, then Boolean expression) is repe

until Boolean expression is false. As Boolean expression evaluates false, loop is termina

ample:

blic class demo {

ublic static void main(String args[]) {

for(int a = 10; a < 20; a = a+1) {

System.out.print("value of a : " + a );

}

is program results in printing value of a from 10 to 19. Because as a is incremented to 20 , the

ndition a


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hile ( Boolean_expression)

/body of the While Loop

he Boolean expression is true then the body defined for the While loop is executed and this rep

ecution for same body continues until the Boolean expression is evaluated to false.

the loop terminates or the Boolean-expression is false , the control is transferred to the first

tement following the while loop.

ample:

r the last given example of for loop, corresponding While Loop is given below.blic class Demo1 {


int a= 10;

while( a < 20 ) {

System.out.print("value of a : " + a);

a++;

}

e do...while Loop

is loop is similar to other loops with a major difference that this loop is always executed at le

ce while the other for and While loops are executed only when condition or Boolean expressio

e. For and while loop may be executed for Zero times if the condition is false.

ntax:

/body for the loophile ( Boolean_expression);

nce this loop has the testing condition at the end of loop , the loop is executed at least once alw

e execution of this loop is otherwise very similar to While loop. Firstly loop is executed and t

olen_expression is evaluated. If expression is true then loop is executed again and again until

olean expression is false.

ample:

milar program for printing value of a from 10 to 19 using do….. while loop is given below.


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blic class demo2 {


int a = 10;

do{

System.out.print("value of a : " + a );

a++;}while( a< 20 );

hanced for loop

hanced for loop is mainly used in case of arrays.ntax:

(declaration : expression)

/ Body for enhanced for loop

pression in the above given syntax generally represents the array which is nneeded to lop throu

is expression is either an array variable or a method call returning array.

claration is a block variable with the same type as the array we are accessing. This variable h

scope within this for block with a value equal to current array element.

ample:

blic class Demo {


int [] values = {10, 20, 30, 40, 50};

for(int a : values ){

System.out.print( a );

System.out.print(" ");

}

System.out.print("\n");

String [] students ={"James", "Anil", "Tom", "Aman"};

for( String name : students ) {

System.out.print( name );

System.out.print(" ");


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}

sult:

20 30 40 50

mes Anil Tom Aman

eak Keyword

va provides break keyword which is used to terminate the entire loop. This keyword can be uide a loop or switch statement to terminate that lop or switch.

ep in mind that in case of nested loops, break keyword only terminates the execution of innerm

op transferring the execution to the first statement following that loop.

ample:

blic class Demo {

blic static void main(String args[]) {int [] values = {10, 20, 30, 40, 50};

for(int a : values) {

if( a == 40 ) {

break;

}



}

tput:

the value of a is equal to 40 , the break statement executes and terminates the loop.

ntinue Keyword

ntinue keyword can be used in any loop structure for deciding the execution control.

When continue is used in for loop then the control is immediately transferred to the

update statement without executing the statements after continue.


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In case of while or do-while, control is immediately transferred to the Boolean

expression without executing the statements after continue.

ample:

blic class Continue {


int [] values = {10, 20, 30, 40, 50};

for ( int a : values ) {

if( a == 40) {

continue;

}



}

is would produce the following result:

hen the value of a is equal to 40, the continue statement executes which transfers the control at

ginning of loop without printing the value of a equal to 40.


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Chapter 4;

Classes, objects and methodsJava is a pure object – oriented language, all java programs have at least a class. Everything

nt to represent through a Java program must be encapsulated in a class. Classes define the stat

haviors for the basic component of a class known as objects. Here the object – oriented refers

sses create objects and the objects uses the defined methods for their mutual communication.

nce Java is an object-oriented language and therefore supports the following feature:

Objects

Classes

Encapsulation

Abstraction

Polymorphism

Instance

Methods

ass: A class is a user-defined data type which acts as a blueprint to represent the states and

haviors for the corresponding objects.

bject: Objects are instances of a class and have their own states and behaviors. For example aect dog for an animal class has state as name, color, breed and behaviors as eating, barking an

gging.

ere are a number of objects in our surroundings which include dog, human, table, bird, mobile

l these objects have their specific states and behaviors.

case of a person as object, corresponding states are name, color, height, age and behaviors are

ing, walking, running, etc.

fining a class

ass is a user defined data type serving as a blueprint. A simple class is defined with the follow

m:

ass classname

ta members or fields declaration; // optional

ethods or member functions declaration; // optional


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data members and member functions are optional, so Java allows even an empty class.

elds and Methods declaration

we know, data is encapsulated in Java by placing its data members and member functions ins

ss. These variables are known as instance variables as they are created as an object is instant

e method of declaring instance variables is same as local variables.

ass Person

age;

ing name;

ing color;

is class has three instance variables one age of integer type and other two name and color of st

e.

claring Methods

method declaration generally has the following things:

Name for the method

Return type of that method

List of arguments or parameters

Body for that method which actually defines the operations to be performed on data

e general form for method declaration is

urnType MethodName ( argument-list)

dy for the method;

class can have following types of variables:

Instance variables: The variables defined inside a class but outside any method are

known as instance variables. As a class is loaded, these variables are instantiated. These

variables can be accessed from any method or block including constructor of that particu

class.

Local variables: The variables defined inside any method, constructor or blocks are

known as local variables. The variable are declared and initialized within a particular

method and destroyed with the completion of that method.

Class variables: These variables are defined inside a class but outside any method

a single difference that they are declared using Static keyword.


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the above given example name, color, age are data member and eating, hungry, walking, runnin

eping all these are functions.

ample for a class

blic class Person {

ing Name;

ing color;

nt age;

oid eating(){

oid hungry(){

void Walking (){

d Running (){

oid sleeping(){

eating Objects for a class

we know objects are the instances of the classes. Creating a object is also known as instantiatobject.

va provides a new operator for creating object. New operator creates an object for the specifss and also returns a reference for that created object. As this returns a reference of class type

refore there is aneed to create a reference type variable so that that can hold that reference.

ample for creating object for class squareuare s1; // declaring object

= new square(); // instantiate object

st statement declares a reference type variable to store the object reference of square type

hereas second statements actually assigns the object reference to S1 variable.

ese both statements can be combined in a single statement to create an object as

uare s1= new square();

th the above given method, we can create any number of objects for a class.

onstructors


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nstructor is the most important topic which comes into the mind as there is a discussion ab

ss. Every class has at least one constructor. If a programmer does not explicitly specify

nstructor, there is always a default constructor for that class. As a object is created, a construc

voked.

portant points for a constructor

Constructor has the same name as class.

There is no return type for a constructor even not void. There can be multiple constructors for a single class.

If constructors are explicitly defined by the programmer then default constructo

comes in existence.

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