What are order of precedence and associativity, and how are they used

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Order of precedence determines the order in which operators are evaluated in expressions.

Associatity determines whether an expression is evaluated left-to-right or right-to-left.

In Java, operators have a specific order of precedence and associativity, which determine the sequence in which multiple operators are evaluated within an expression.

Order of Precedence: The order of precedence defines the priority of operators in an expression. Operators with higher precedence are evaluated before operators with lower precedence. For example, the multiplication operator (*) has higher precedence than the addition operator (+). If both operators are present in an expression, the multiplication will be performed first.

Here is a simplified list of some operators in Java along with their general order of precedence (from highest to lowest):

  1. Postfix operators: expr++ and expr--
  2. Unary operators: ++expr, --expr, +expr, -expr, ~, !
  3. Multiplicative operators: *, /, %
  4. Additive operators: +, -
  5. Shift operators: <<, >>, >>>
  6. Relational operators: <, <=, >, >=, instanceof
  7. Equality operators: ==, !=
  8. Bitwise AND: &
  9. Bitwise XOR: ^
  10. Bitwise OR: |
  11. Logical AND: &&
  12. Logical OR: ||
  13. Conditional operator (Ternary): ? :
  14. Assignment operators: =, +=, -=, *=, /=, %= etc.

Associativity: Associativity defines the grouping of operators with the same precedence. It determines whether an expression is evaluated from left to right or from right to left when operators have the same precedence. Most operators in Java are left-associative, meaning they are evaluated from left to right. The assignment operators, for example, are right-associative.

For example, consider the following expression:

java
int result = 5 * 3 + 2;

The multiplication (*) has higher precedence, so it will be performed first, resulting in:

java
int result = (5 * 3) + 2;

Then the addition (+) is performed. If the operators had the same precedence and were left-associative, the expression would be evaluated as (5 * 3) + 2. If they were right-associative, it would be evaluated as 5 * (3 + 2).

Understanding the order of precedence and associativity is crucial for writing correct and predictable expressions in Java. It ensures that expressions are evaluated in the intended order, and grouping is done as expected.