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8/13/2019 Introduction to programming using JAVA - lecture 3
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8/13/2019 Introduction to programming using JAVA - lecture 3
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[email protected]@cmb.ac.lkUCSC 2005. All rights reserved. No part of this material may be reproduced and sold.
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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
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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
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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.
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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;
8/13/2019 Introduction to programming using JAVA - lecture 3
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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
8/13/2019 Introduction to programming using JAVA - lecture 3
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Special OperatorsSpecial Operators
class SpecialArithmetic {
public static void main (String args[]) {
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
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Bitwise OperatorsBitwise Operators
Operator Meaning
& Bitwise AND
| Bitwise OR^ Bitwise XOR
>> Right Shift
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Bitwise OperatorsBitwise Operators
Bit-wise Operators
Operator Meaning
x &= y AND Assignmentx |= y OR Assignment
x ^= y XOR Assignment
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Bitwise OperatorsBitwise Operators
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
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Bitwise OperatorsBitwise Operators
class Shift {
public static void main (String args[]) {
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
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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.
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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;
}
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Control StatementsControl Statements
True False
If - else Statement Contd..
Statement bStatement d
Statement cStatement a
Expression
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Conditional Operator ?:Conditional Operator ?:
Expression ? Statement 1 : Statement 2
If expression is true If expression is false
X= ((marks>50) ? Pass : Failed);
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Logical OperatorsLogical Operators
Operator Operator Meaning
& && Logical AND
| || Logical OR
! Logical NOT
Short Circuit Operators
Condition Operator
Boolean Operators
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Logical OperatorsLogical Operators
|| (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
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Logical OperatorsLogical Operators
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)
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Logical OperatorsLogical Operators
! Operator
Expression Resultcondition ! (condition)
true falsefalse true
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Relational OperatorsRelational Operators
Operator Meaning
!= not equal to== is equal to
< less than> greater than
>= greater than or equal to
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Relational OperatorsRelational Operators
class Relational{
public static void main (String args[]) {
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
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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 +
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Operator PrecedenceOperator Precedence
Operator Precedence
&^
|
&&||
?:= += - = ect.
&= |=
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Operator PrecedenceOperator Precedence
Notes on Operator Precedence
General order of evaluation is
Increment,Decrement operators
Arithmetic Operators
Comparison Operators
Logical Operators,
Assignment Operators
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Operator PrecedenceOperator Precedence
Notes on Operator Precedence
Order of evaluation can be changed by usingParenthesis
(3+2) will beEvaluated FirstEg: (3+2) / 2 +6
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