These operators operate on boolean operands and result
is also boolean. Like relational and equality, they are also
used frequently in if blocks and different loop for decision
making.
Operator Description
& Logical AND : evaluates to true if both operands evaluate to true
Logical OR : evaluates to true if both operands evaluate to true
^ Logical XOR : evaluates to true if odd no of operands are true
Short circuit OR
&& Short circuit AND
! Unary NOT
?: Ternary
Difference between & and &&
& : It evaluates both the operands
&& : It won't evaluate the second operand if the first operand evaluates to false
Example
Case 1
boolean flag = false ;
int count = 5 ;
if (flag & count ++ < 6)
{
// something
}
System.out.println (i) ; // count is 6 here
Case 2
boolean flag = false ;
int count = 5 ;
if (flag && count ++ < 6)
{
// something
}
System.out.println (i) ; // count is 5 here
In the second case, short circuit AND is used.When flag
evaluates to false, it does not go to the second part of
expression. Hence count ++ is not executed
Difference between and
: It evaluates both the operands
: It won't evaluate the second operand if the first operand evaluates to true
You can work it out on the lines of above example
Unary NOT
- It simply returns toggled value of it's operand.
- Operand remains unaffected.
boolean flag = false ;
if (! flag)
{
System.out.println ("flag still false " + flag) ;
}
Here, if block would be executed as NOT operator returns true but
flag still holds false
Ternary operator
General syntax is
exp ? statement 1 : statement 2
exp: expression evaluating to a boolean
If exp evaluates to true statement 1 is executed
otherwise statement 2
It can be thought of of as a shorthand for if else block
