The concepts explained in this book are very important. Don’t worry if you find the concepts confusing. You can always come back and view the video later.
You can combine operators to form complex expessions.
The order in which the operations are evaluated is determined by the precedence of the operators involved in the expression. For example, multiplication and division have a higher precedence than addition and subtraction.
Always remember, precedence rules can be overridden by explicit parentheses.
Parentheses raise the precedence of the operations that are inside them. This is often necessary to obtain the result you desire.
When two operators share an operand the operator with the higher precedence goes
first. For example, 1 + 2 * 3(1 plus 2 into 3) is treated as 1 + (2 * 3),
whereas 1 * 2 + 3 is treated as (1 * 2) + 3 since multiplication has a higher
precedence than addition.
But what happens when two operators with the same precedence occur in the same expression? In such cases, the expression is evaluated according to the associtivity of the operators involved.
For example, the expression x = y = z = 7 is equivalent to x = (y = (z = 7))
because the assignment operator has right-to-left associativity which means the
operators are evaluated from left to right.
Here’s another example. The expression 10 / 20 / 30 is equivalent to
(10 / 20) / 30 because the / division operator has left-to-right associativity.
Further, some operators are associative. For example, the expression
(x <= y <= z) is invalid.
The following table shows all operators in Java from highest to lowest precedence, along with their associativity. You don’t have to memorize them all. You will learn eventually with practise.
| Precedence | Operator | Type | Associativity |
|---|---|---|---|
| 14 | () | Parentheses | left-to-right |
| [] | Subscript | ||
| ยท | Member selection | ||
| 13 | + | Unary plus | right-to-left |
| - | Unary minus | ||
| ! | Logical NOT | ||
| ~ | Bitwise NOT | ||
| 12 | * | Multiplication | left-to-right |
| / | Division (quotient) | ||
| % | Division (remainder) | ||
| 11 | + | Addition | left-to-right |
| - | Subtraction | ||
| 10 | << | Bitwise left shift | left-to-right |
| >> | Bitwise right shift with sign extension | ||
| >>> | Bitwise right shift with zero extension | ||
| 9 | < | Lesser than | left-to-right |
| <= | Lesser than or equal | ||
| > | Greater than | ||
| >= | Greater than or equal | ||
| instanceof | Check Instance Type | ||
| 8 | == | Equality | left-to-right |
| != | Inequality | ||
| 7 | & | Bitwise AND | left-to-right |
| 6 | ^ | Bitwise Exclusive OR | left-to-right |
| 5 | | | Bitwise Inclusive OR | left-to-right |
| 4 | && | Logical AND | left-to-right |
| 3 | || | Logical OR | left-to-right |
| 2 | ? : | Conditional | right-to-left |
| 1 | = | Assignment | |
| += | Addition and assignment | ||
| -= | Subtraction and assignment | ||
| *= | Multiplication and assignment | ||
| /= | Division (quotient) and assignment | ||
| &= | Bitwise AND and assignment | ||
| ^= | Bitwise XOR and assignment | ||
| |= | Bitwise OR and assignment | ||
| ~= | Bitwise NOT and assignment |
We recommend you to use parentheses whenever possible for clarity.