Now that you've learned how to declare and initialize variables, you probably want to know how to
do something with them. Learning the operators of the Java programming language is a good place to start. Operators are special symbols that perform specific operations on one, two, or three
operands, and then return a result.
As we explore the operators of the Java programming language, it may be helpful for you to know ahead of time which operators have the highest precedence. The operators in the following table are listed according to precedence order. The closer to the top of the table an operator appears, the higher its precedence. Operators with higher precedence are evaluated before operators with relatively lower precedence. Operators on the same line have equal precedence. When operators of equal precedence appear in the same expression, a rule must govern which is evaluated first. All binary operators except for the assignment operators are evaluated from left to right; assignment operators are evaluated right to left.
Operator Precedence
| Operators | Precedence |
|---|
| postfix | expr++ expr-- |
| unary | ++expr --expr +expr -expr ~ ! |
| multiplicative | * / % |
| additive | + - |
| shift | << >> >>> |
| relational | < > <= >= instanceof |
| equality | == != |
| bitwise AND | & |
| bitwise exclusive OR | ^ |
| bitwise inclusive OR | | |
| logical AND | && |
| logical OR | || |
| ternary | ? : |
| assignment | = += -= *= /= %= &= ^= |= <<= >>= >>>=
|
The Arithmetic Operators
The Java programming language provides operators that perform addition, subtraction, multiplication, and division. There's a good chance you'll recognize them by their counterparts in basic mathematics. The only symbol that might look new to you is "%", which divides one operand by another and returns the remainder as its result.
| Operator | Description |
|---|
+ | Additive operator (also used for String concatenation) |
- | Subtraction operator |
* | Multiplication operator |
/ | Division operator |
% | Remainder operator
|
The Unary Operators
The unary operators require only one operand; they perform various operations such as incrementing/decrementing a value by one, negating an expression, or inverting the value of a boolean.
| Operator | Description |
|---|
+ | Unary plus operator; indicates positive value (numbers are positive without this, however) |
- | Unary minus operator; negates an expression |
++ | Increment operator; increments a value by 1 |
-- | Decrement operator; decrements a value by 1 |
! | Logical complement operator; inverts the value of a boolean |
The Equality and Relational Operators
The equality and relational operators determine if one operand is greater than, less than, equal to, or not equal to another operand. The majority of these operators will probably look familiar to you as well. Keep in mind that you must use "
==", not "
=", when testing if two primitive values are equal.
== equal to
!= not equal to
> greater than
>= greater than or equal to
< less than
<= less than or equal to
The Conditional Operators
The && and || operators perform Conditional-AND and Conditional-OR operations on two boolean expressions. These operators exhibit "short-circuiting" behavior, which means that the second operand is evaluated only if needed.
&& Conditional-AND
|| Conditional-OR
class ConditionalDemo1 {
public static void main(String[] args){
int value1 = 1;
int value2 = 2;
if((value1 == 1) && (value2 == 2))
System.out.println("value1 is 1 AND value2 is 2");
if((value1 == 1) || (value2 == 1))
System.out.println("value1 is 1 OR value2 is 1");
}
}
Another conditional operator is
?:, which can be thought of as shorthand for an
if-then-else statement (discussed in the
Control Flow Statements section of this lesson). This operator is also known as the
ternary operator because it uses three operands. In the following example, this operator should be read as: "If
someCondition is
true, assign the value of
value1 to
result. Otherwise, assign the value of
value2 to
result."
class ConditionalDemo2 {
public static void main(String[] args){
int value1 = 1;
int value2 = 2;
int result;
boolean someCondition = true;
result = someCondition ? value1 : value2;
System.out.println(result);
}
}
Because someCondition is true, this program prints "1" to the screen. Use the ?: operator instead of an if-then-else statement if it makes your code more readable; for example, when the expressions are compact and without side-effects (such as assignments).
