What are the priority levels of arithmetic operations in Java?

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In Java, arithmetic expressions often contain multiple operators. Understanding the priority (or precedence) of these operators is crucial to determine the order in which operations are performed. Without this knowledge, arithmetic calculations could yield incorrect results.

🔍 What is it?

In Java, operator precedence determines the order in which arithmetic operations are evaluated in an expression. Operators with higher precedence are executed before those with lower precedence. If multiple operators have the same precedence, associativity defines the order of evaluation.

Priority Levels of Arithmetic Operators in Java:

  1. Highest Precedence:
  2. () (Parentheses):

Parentheses have the highest precedence and are used to explicitly define the order of operations in an expression. Operations within parentheses are evaluated first, regardless of other operators' precedence.
3. Example:

java int result = (2 + 3) * 4; // Parentheses first: (2 + 3) = 5, then 5 * 4 = 20

  1. Next Highest Precedence:
  2. Unary Operators: +, - (Unary Plus/Minus)

These operators indicate the sign of a number. They have higher precedence than multiplication, division, and addition/subtraction.
3. Example:

java int result = -5 + 3; // Unary minus: (-5) + 3 = -2

  1. Multiplication/Division/Modulus:
  2. * (Multiplication), / (Division), % (Modulus):

These operators have the same precedence and are evaluated left to right (left-associative). If these operators appear together, they are executed in the order they appear from left to right.
3. Example:

java int result = 10 / 2 * 3; // Left to right: 10 / 2 = 5, then 5 * 3 = 15

  1. Addition/Subtraction:
  2. + (Addition), - (Subtraction):

Addition and subtraction operators have lower precedence than multiplication, division, and modulus. Like the above operators, they are also left-associative.
3. Example:

java int result = 5 + 3 - 2; // Left to right: 5 + 3 = 8, then 8 - 2 = 6

Summary of Arithmetic Operator Precedence (Highest to Lowest):

  1. Parentheses: ()
  2. Unary Plus/Minus: +, -
  3. Multiplication/Division/Modulus: *, /, %
  4. Addition/Subtraction: +, -

Associativity:

  • Left to right: Operators like +, -, *, /, and % are evaluated left to right if they appear consecutively in an expression.
  • Right to left: Unary operators (+, -) are evaluated from right to left.

Example Combining Precedence and Associativity:

int result = 10 - 3 * 2 + (4 / 2);

  • First, evaluate parentheses: (4 / 2) = 2
  • Then, evaluate multiplication: 3 * 2 = 6
  • Now, subtraction and addition (left to right):

10 - 6 = 4, then 4 + 2 = 6

Final result: 6

Why It Matters:

Understanding operator precedence helps you avoid logical errors in complex expressions. Parentheses can always be used to override the default precedence to ensure that operations are performed in the desired order.

In conclusion, arithmetic operations in Java follow a specific precedence order, with parentheses having the highest priority, followed by unary operators, multiplication/division/modulus, and finally, addition/subtraction. Using parentheses helps clarify or override default precedence rules in complex expressions.