Java Operators
Java provides a rich set
of operators to manipulate variables. There are different types of operators. There are arithmetic operators, relational operators, logical operators and
conditional operators. These operators follow a certain kind of precedence
so that the compiler will know which operator to evaluate first in case
multiple operators are used in one statement.
a 1. Arithmetic Operators
–
are
used in mathematical expressions in the same way that they are used in algebra.
a.1. Increment and Decrement Operators
·
Aside
from the basic arithmetic operators, Java also includes a unary increment
operator (++) and unary decrement operator (--). Increment and decrement
operators increase and decrease a value stored in a number variable by 1.
·
For
example, the expression,
count = count + 1; //increment the value of count by 1
·
is
equivalent to:
count++;
·
The
increment and decrement operators can be placed before or after an operand.
·
When
used before an operand, it causes the variable to be incremented or decremented by
1, and then the new value is used in the expression in which it appears. For
example:
int i = 10,
int j = 3;
int k = 0;
k = ++j + i; //will result to k = 4+10 = 14
·
When
the increment and decrement operators are placed after the operand, the old
value of the variable will be used in the expression where it appears. For
example:
int i = 10,
int j = 3;
int k = 0;
k = j++ + i; //will result to k = 3+10 = 13
b 2. Relational Operators
o compare two values and determines the relationship between those values
o the output of evaluation are the boolean values true or false.
c 3. Logical Operators
–
have
one or two boolean operands that yield a boolean result
–
There
are six logical operators: &&
(logical AND), & (boolean logical AND), || (logical OR), |(boolean logical
inclusive OR), ^ (boolean logical exclusive OR), and ! (logical NOT).
–
The
basic expression for a logical operation is:
x1 op x2
–
where x1, x2 can be boolean expressions,
variables or constants, and op is
either &&, &, ||, |or ^ operator
c.1. Logical
AND (&&) and Boolean Logical AND(&)
c.2.
Logical OR (||) and Boolean Logical OR (|)
c.3.
Boolean Logical Exclusive OR(^) and Logical NOT (!)
d 4. Conditional
Operator
–
the
conditional operator (?:) is a ternary operator
o this means that it takes in three arguments that
together form a conditional expression
–
the
structure of an expression using a conditional operator is,
exp1?exp2:exp3
–
wherein
exp1 is a boolean expression whose
result must either be true or false
–
if exp1 is true, exp2 is the value
returned. If it is false, then exp3 is returned.
–
For
example, given the code:
public class
ConditionalOperator
{
public static void main(String[] args){
String status = "";
int grade = 80;
//get status of the student
status = (grade >= 60)?"Passed":"Fail";
//print status
System.out.println(status);
}
}
–
The
output of this program will be:
Passed
–
Here
is another program that uses the ?: operator:
class
ConditionalOperator
{
public static void main(String[] args){
int score = 0;
char answer = 'a';
score = (answer == 'a') ? 10 : 0;
System.out.println("Score = " + score );
}
}
–
The
output of the program is:
Score = 10
e Operator Precedence
–
it
defines the compiler’s order of evaluation of operators so as to come up with
an unambiguous result
–
Given
a complicated expression:
6%2*5+4/2+88-10
–
we can
re-write the expression and place some parenthesis base on operator precedence:
((6%2)*5)+(4/2)+88-10
TRY THIS: Sample Exercises
1 A. Declaring and printing variables
Given the table below, declare the following variables with the
corresponding data types and initialization values. Output to the screen the
variable names together with the values.
The following should
be the expected screen output:
The number is 10.
My letter is ‘a’.
The result is true.
My string is “hello”.
2 B. Getting the average of three numbers
Create a program that outputs the average of three numbers. Let the
values of the three numbers be, 10, 20 and 45. The expected screen output is,
number 1 = 10
number 2 = 20
number 3 = 45
Average is = 25
3. Given three numbers, write a program that outputs the number with the
greatest value among the three. Use the conditional ?: operator that we have
studied so far (HINT: You will need to use two sets of ?: to solve this). For example, given the
numbers 10, 23 and 5, your program should output,
number 1 = 10
number 2 = 23
number 3 = 5
The highest number is
= 23
Happy Coding guys! Happy Programming!
