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Module: Variables and Data Types

Operators

Java Core: Operators

Operators are special symbols that perform specific operations on operands (values or variables). Java provides a rich set of operators to perform arithmetic, logical, relational, bitwise, and other operations.

1. Arithmetic Operators

These operators perform mathematical calculations.

Operator Description Example Result
+ Addition 5 + 3 8
- Subtraction 5 - 3 2
* Multiplication 5 * 3 15
/ Division 5 / 3 1 (Integer division truncates the decimal part)
% Modulus (Remainder) 5 % 3 2
++ Increment (Adds 1 to the operand) int x = 5; x++; x becomes 6
-- Decrement (Subtracts 1 from the operand) int x = 5; x--; x becomes 4

Important Notes:

  • Division (/) with integers results in integer division (truncating the decimal part). To get a floating-point result, at least one operand must be a floating-point type (e.g., 5.0 / 3).
  • ++ and -- can be used as prefix (++x) or postfix (x++) operators. The difference lies in when the increment/decrement happens relative to the expression's evaluation.
    • Prefix: Increment/decrement before the value is used in the expression.
    • Postfix: Increment/decrement after the value is used in the expression.
int x = 5;
int y = x++; // y = 5, x = 6 (postfix)

int a = 5;
int b = ++a; // a = 6, b = 6 (prefix)

2. Assignment Operators

These operators assign values to variables.

Operator Description Example Equivalent to
= Assignment x = 5;
+= Add and Assign x += 5; x = x + 5;
-= Subtract and Assign x -= 5; x = x - 5;
*= Multiply and Assign x *= 5; x = x * 5;
/= Divide and Assign x /= 5; x = x / 5;
%= Modulus and Assign x %= 5; x = x % 5;

3. Relational Operators

These operators compare two operands and return a boolean value (true or false).

Operator Description Example Result (if x = 5, y = 10)
== Equal to x == y false
!= Not equal to x != y true
> Greater than x > y false
< Less than x < y true
>= Greater than or equal to x >= y false
<= Less than or equal to x <= y true

4. Logical Operators

These operators combine boolean expressions.

Operator Description Example Result (if x = true, y = false)
&& Logical AND x && y false (true only if both operands are true)
` ` Logical OR
! Logical NOT !x false (inverts the boolean value)

Short-Circuiting:

Java's logical operators use short-circuiting. This means:

  • &&: If the left operand is false, the right operand is not evaluated.
  • ||: If the left operand is true, the right operand is not evaluated.

5. Bitwise Operators

These operators work on the individual bits of integer operands.

Operator Description Example
& Bitwise AND 5 & 3 (0101 & 0011 = 0001 = 1)
` ` Bitwise OR
^ Bitwise XOR (Exclusive OR) 5 ^ 3 (0101 ^ 0011 = 0110 = 6)
~ Bitwise NOT (One's Complement) ~5 (Inverts all bits)
<< Left Shift 5 << 2 (0101 << 2 = 10100 = 20)
>> Right Shift (Sign-Extending) 5 >> 2 (0101 >> 2 = 0001 = 1)
>>> Right Shift (Zero-Extending) 5 >>> 2 (0101 >>> 2 = 0001 = 1)

6. Ternary Operator (Conditional Operator)

This is a shorthand for an if-else statement.

Operator Description Example
? : Conditional int result = (x > y) ? x : y; (If x > y, result = x; otherwise, result = y)

7. Operator Precedence

Operators have a precedence order that determines the order in which operations are performed. Here's a simplified order (highest to lowest):

  1. Parentheses ()
  2. Unary operators (++, --, !, ~)
  3. Multiplication, Division, Modulus (*, /, %)
  4. Addition, Subtraction (+, -)
  5. Shift operators (<<, >>, >>>)
  6. Relational operators (==, !=, >, <, >=, <=)
  7. Logical operators (&&, ||)
  8. Ternary operator ? :
  9. Assignment operators (=, +=, -=, etc.)

Use parentheses to explicitly control the order of operations when needed.

Example:

int result = 5 + 3 * 2; // result = 11 (Multiplication before addition)
int result2 = (5 + 3) * 2; // result2 = 16 (Addition before multiplication)

This comprehensive overview should give you a solid understanding of operators in Java. Remember to practice using them to become comfortable with their behavior.