Chapter 4 - Operators Flashcards
Relational operators
always result in a boolean value (true or false)
There are 6 relational operators
> >= < <= == (Equality Operator) != (Equality Operator)
Equality Operators
There are two: == and !=
4 things can be tested:
numbers, characters, booleans and reference variables
When comparing characters
Java uses Unicode value of character as the numeric value
instanceof operator
is for reference variables only, and checks if an object is of a particular type
instanceof operator
can be used only to test Objects (or null) against class types that are of the same hierarchy
for interfaces
an object passes the instanceof test if any of its superclasses implement the interface on the right side of the instanceof operator
There are 4 primary math operators
add, subtract, multiply and divide
The remainder operator (%)
returns the remainder of a division
Expressions are evaluated from left to right
unless you add parenthesis, or unless some operators have higher precedence
*,/, and %
operators have higher precedence than + and -
If either operand is a string
the + operator concatenates the operands
If both operands are numeric (in string concatenations)
the + operator adds the operands
Prefix operators ++ and – run
before the value is used in the expression
Postfix operators ++ and – run
after the value is used in the expression
In any expression
both operands are fully evaluated before the operator is applied
Variables marked final
cannot be incremented or decremented
Ternary/Conditional operators returns
one of two values based on whether boolean expression is true or false
returns the value after the ? if expression is true
returns the value after the : if expression is false
The exam covers 6 ternary operators
&, |, ^, !, &&, and ||
Logical operators work with two expressions
except for (!) that must resolve to boolean values
The && and & operators
return true only if BOTH operands are true
The || and | operators
returns true if EITHER or BOTH operands are true
The && and ||
are known as SHORT CIRCUIT operators
The && operand does not evaluate the right operand
if the left operand is false
The || operand does not evaluate the right operand
if the left operand is true
The & and | operators
always evaluate both operands
The ^ operator (called the logical XOR)
returns true if exactly one operand is true
The ! operator (called the inversion operator)
returns the opposite value of the boolean operand it precedes
