introduction to programming using java - lecture 3

8/13/2019 Introduction to programming using JAVA - lecture 3

1/30


2/30

[email protected]@cmb.ac.lkUCSC 2005. All rights reserved. No part of this material may be reproduced and sold.

2

An operatoris a function that has a special

symbolic name and is invoked by using that

symbol with an expression.Examples of expressions that include

Java operators :

n = 2

n += 3

++nn / 3

n % 3

OperatorsOperators


3/30


3

OperatorsOperators

Assignment Operator (=)

Example

A=15;

num1 = num2 = num3 = A + 5;

Right side of Assignment operator

is evaluated first and then the

Assignment takes place


4/30


5/30


5

Arithmetic OperatorsArithmetic Operators

x = y / 2;

in the above expression, x and y are

variables, 2 is a literal and = and / areoperators.

This expression states that the y variable is

divided by 2 using the division operator (/),and the result is stored in x using the

assignment operator (=).

Notice the expression was described from

right to left. It is how the compiler itself

analyzes expressions to generate code.


6/[email protected]@cmb.ac.lkUCSC 2005. All rights reserved. No part of this material may be reproduced and sold.

6

Arithmetic OperatorsArithmetic Operators

It is also possible to use the shortcuts for arithmetic

operators as given below.a + = b; is the same as a = a + b;

a - = z; is the same as a = a - z;

a * = 9; is the same as a = a * 9;

a / = 3 is the same as a = a / 3;

a % = 3 is the same as a = a % 3;



7

OperatorsOperators

class Arithmetic {

public static void main (String args[]) {

int x=17, y=5;

System.out.println(x=+x);

System.out.println(y=+y);

System.out.println(x+y=+(x+y));

System.out.println(x-y=+(x-y));

System.out.println(x*y=+(x*y));

System.out.println(x/y=+(x/y));

System.out.println(x%y=+(x%y));

}

}

x=17

y=5

x+y=22

x-y=12

x*y=85

x/y=3

x%y=2



8

Special OperatorsSpecial Operators

class SpecialArithmetic {


int x=17,a,b;a=x++;b=++x;

System.out.println(x=+x+ a=+a);

System.out.println(x=+x+ b=+b);a=x--;b=--x;

System.out.println(x=+x+ a=+a);

System.out.println(x=+x+ b=+b);

}

}

x=19 a=17

x=19 b=19

x=18 a=19

x=17 b=17



9

Bitwise OperatorsBitwise Operators

Operator Meaning

& Bitwise AND

| Bitwise OR^ Bitwise XOR

>> Right Shift


10/30



11


Bit-wise Operators

Operator Meaning

x &= y AND Assignmentx |= y OR Assignment

x ^= y XOR Assignment



12


class Bitwise {

public static void main (string args[]) {

int x=5, y=6;System.out.println(x=+x);

System.out.println(y=+y);

System.out.println(x&y=+(x&y));

System.out.println(x|y=+(x|y));

System.out.println(x^y=+(x^y));

}

}

x=5

y=6

x&y=4

x|y=7

x^y=3



13


class Shift {


int x=7;

System.out.println(x=+x);

System.out.println(x >>2=+(x>>2);System.out.println(x>>1));}

}

x=7

y>>2=1

x>1=3


14/30


14

Control StatementsControl Statements

Control Statements

If ....Else Statements

if ( Expression )

statement1;

elsestatement2;

If Expression true then statement1 is executed;

otherwise statement2 is executed. else is optional.


15/30


15

If ..else statementsIf ..else statements

If more Statements are to be performed, all the

statements should be included within curly brackets.

If ( Expression) {

statement a;

statement b;

}

else { statement c;

statement d;

}


16/30


16

Control StatementsControl Statements

True False

If - else Statement Contd..

Statement bStatement d

Statement cStatement a

Expression


17/30


17

Conditional Operator ?:Conditional Operator ?:

Expression ? Statement 1 : Statement 2

If expression is true If expression is false

X= ((marks>50) ? Pass : Failed);


18/30


18

Logical OperatorsLogical Operators

Operator Operator Meaning

& && Logical AND

| || Logical OR

! Logical NOT

Short Circuit Operators

Condition Operator

Boolean Operators


19/30


20/30


20


|| (Logical OR) Operator

Expression Result

condition 1 condition 2 condition 1 || condition 2

(You know politico?) OR (You know thugs?) (You are rich)

true true true

false true truetrue false true

false false false


21/30


21


When evaluating && and ||, Java will stop the

evaluation of the rest of the expression as soon as

the outcome becomes clear.

In (dnom!=0 && num / denom>10)

second part will not be evaluated if (dnom =0)


22/30


22


! Operator

Expression Resultcondition ! (condition)

true falsefalse true


23/30


23

Relational OperatorsRelational Operators

Operator Meaning

!= not equal to== is equal to

< less than> greater than

>= greater than or equal to


24/30


24

Relational OperatorsRelational Operators

class Relational{


int x=7, y=11, z=11;

System.out.println(x=+x);System.out.println(y=+y);

System.out.println(z=+z);

System.out.println(xy));

System.out.println(y=y));

System.out.println(y==z =+(y==z));

System.out.println(x!=y =+(x!=y));

}

}

x=7

y=11

z=11

xz=false

y=y =false

y==z =true

x!=y =true


25/30


25

Operator PrecedenceOperator Precedence

Determines the order in which expressions are

evaluated

ExampleExampley = 6+ 3*2

the value of y will be 12 because 3*2 will

be evaluated first as * has a higher precedence

than +


26/30


27/30


27


Operator Precedence

&^

|

&&||

?:= += - = ect.

&= |=


28/30


28


Notes on Operator Precedence

General order of evaluation is

Increment,Decrement operators

Arithmetic Operators

Comparison Operators

Logical Operators,

Assignment Operators


29/30


29


Notes on Operator Precedence

Order of evaluation can be changed by usingParenthesis

(3+2) will beEvaluated FirstEg: (3+2) / 2 +6


30/30

introduction to programming using java - lecture 3

Documents