Last Updated on November 29, 2023 by Ankit Kochar
In Java, operator precedence refers to the order in which operators are evaluated in expressions. When an expression involves multiple operators, Java follows a specific set of rules to determine the order in which these operators are applied. Understanding operator precedence is crucial for writing correct and efficient code, as it ensures that expressions are evaluated in the intended order.
This introduction will delve into the importance of operator precedence in Java, how it affects the outcome of expressions, and how developers can use it to write clear and concise code.
Precedence of Operators
Having understood how we can tackle solving an expression with the precedence of operators that decides the order of execution. In this section of this article on Java Operator Precedence, let us look at how the operators fare in the table given below:
|2||||Array access and member access|
|3||++ —||Postfix increment/decrement|
|4||++ — + – ! ~||Prefix increment/decrement, unary plus/minus, logical negation/complement|
|5||* / %||Multiplication, division, and remainder|
|6||+ –||Addition and subtraction|
|7||<> >>>||Bitwise shift operators|
|8||< >=||Relational operators|
|9||\== !=||Equality operators|
|11||^||Bitwise exclusive OR|
|12||I||Bitwise inclusive OR|
|16||\= += -= *= /= %= &= ^=||= <>= >>>=||Assignment operators|
In the above table, lower rank indicates higher precedence, as parenthesis having a rank of first will be first in the order of execution.
As we discussed Operators with higher precedence are evaluated before operators with lower precedence. For example, in the expression a + d c, the multiplication operator () has higher precedence than the addition operator (+), so the multiplication is performed first.
Handling Same Precedence with Associativity
In case there are operators sharing the same rank then the tiebreaker is performed by taking associativity into consideration which is either left to right or right to left.
The evaluation of operators from left to right is known as left-to-right associativity. For instance, in the expression a – b – c, the subtraction operators are evaluated from left to right, resulting in (a – b) – c.
On the other hand, right-to-left associativity pertains to the evaluation of operators from right to left. An example of this is the assignment operator =, which has right-to-left associativity. Thus, in the expression a = b = c, the assignment is executed from right to left, and the expression is equivalent to a = (b = c).
|Left-to-right||+ – * / % <> >>> < >= instanceof|
|Left-to-right||\== != & ^||&&|
|Right-to-left||\= += -= *= /= %= &= ^=||= <>= >>>=|
|Right-to-left||? : ++ — + – ! ~ (type) new  .|
The above table can be essential in determining the output in similar java operator precedence. So with the combination of associativity and precedence, it becomes easy for us to understand how expressions are evaluated in java.
Impact of Parenthesis on Precedence
In certain scenarios, it may be necessary to alter the default operator precedence and prioritize the evaluation of a specific expression. One way to achieve this is by utilizing parentheses.
Expressions enclosed in parentheses are evaluated before any other expressions, regardless of their default precedence. For instance, consider the expression (a + b) * c. Although multiplication has a higher precedence, the addition operation is executed first because it is enclosed in parentheses.
The order of evaluation in terms of Java Operator Precedence can be altered with the use of parenthesis no matter what the operator precedence is. It can be understood with the help of the following example:-
int result = (13 + 5) * 1 - 3 / 1;
In this expression, the addition is evaluated first because of the parentheses, resulting in 18 * 1 – 3, which evaluates to 15.
Understanding Operator Precedence in Java
Now that we have an idea of what Java Operator Precedence stands for. Let us take an example to understand how the Java Operator Precedence works in an expression.
Suppose we have an expression,
int result = 13 + 5 * 1 - 3 / 1;
In this expression, the operators are evaluated in the following order: For the first step, 5 * 1 is evaluated first because multiplication has higher precedence than addition and subtraction.
In the second step, 3 / 1 is evaluated next because division has higher precedence than addition and subtraction.
The results of the first and second steps are then used to perform the addition and subtraction in left-to-right order. So 13 + 5 – 3 is evaluated to give a final result of 15.
Example of Operator Precedence in Java:
Suppose we have the expression 5 * 3 + 10 / 2 – 4, and we want to evaluate it according to operator precedence and associativity rules in Java.
First, we need to identify the operators and their precedence:
Precedence Operators 1 * / % 2 + -
Based on the table, we can see that the multiplication operator () has higher precedence than the addition operator (+), so we evaluate 5 3 first:
5 * 3 + 10 / 2 - 4 15 + 10 / 2 - 4
Next, we need to evaluate the division operator (/), which has the same precedence as the multiplication operator (*), but left-to-right associativity:
15 + 10 / 2 - 4 15 + 5 - 4
Finally, we evaluate the addition operator (+) and the subtraction operator (-), which have the same precedence as each other, but left-to-right associativity:
15 + 5 - 4 16
Therefore, the value of the expression 5 * 3 + 10 / 2 – 4 is 16.
In conclusion, a solid understanding of Java operator precedence is essential for writing robust and error-free code. By grasping the rules governing the order in which operators are evaluated, developers can avoid common pitfalls and ensure that expressions produce the desired results. Whether working on simple arithmetic operations or complex logical expressions, being mindful of operator precedence contributes to code clarity and maintainability.
As you continue to explore Java programming, keep in mind that parentheses can be a powerful tool for explicitly specifying the order of evaluation, especially when dealing with expressions involving multiple operators. Java’s well-defined operator precedence rules provide a foundation for creating reliable and efficient code.
Frequently Asked Questions
Frequently Asked Questions related to Java Operator Precedence are:
Q1: What is operator precedence in Java?
A1: Operator precedence in Java defines the order in which operators are evaluated in expressions. It ensures that expressions are processed correctly by establishing rules for the hierarchy of operators.
Q2: How can I override operator precedence in Java?
A2: Parentheses can be used to override the default operator precedence. Expressions enclosed in parentheses are evaluated first, allowing developers to explicitly control the order of evaluation.
Q3: Are all operators in Java left-associative?
A3: No, not all operators in Java are left-associative. Assignment operators, for example, are right-associative, meaning they evaluate from right to left.
Q4: Why is operator precedence important for Java developers?
A4: Operator precedence is crucial for writing correct and efficient code. Understanding the order in which operators are evaluated ensures that expressions produce the intended results and helps prevent logical errors in code.
Q5: Can I rely on default operator precedence, or should I always use parentheses?
A5: While default operator precedence is reliable, using parentheses can enhance code readability and make the intended order of evaluation explicit. It’s a good practice, especially in complex expressions, to use parentheses to avoid confusion.