What are Operators?
Operators are special symbols that perform operations on variables and values. Java supports a rich set of operators categorized by their functionality.
Arithmetic Operators
Used for mathematical calculations:
java
public class ArithmeticDemo {
public static void main(String[] args) {
int a = 20, b = 7;
System.out.println("a + b = " + (a + b)); // 27 (Addition)
System.out.println("a - b = " + (a - b)); // 13 (Subtraction)
System.out.println("a * b = " + (a * b)); // 140 (Multiplication)
System.out.println("a / b = " + (a / b)); // 2 (Integer Division)
System.out.println("a % b = " + (a % b)); // 6 (Modulus / Remainder)
}
}Note: Integer division truncates the decimal. Use double for precise division: (double) a / b gives 2.857...
Unary Operators
Operate on a single operand:
| Operator | Description | Example |
|---|---|---|
+ | Unary plus | +5 |
- | Unary minus (negate) | -5 |
++ | Increment by 1 | i++ or ++i |
-- | Decrement by 1 | i-- or --i |
! | Logical NOT | !true → false |
Pre vs Post Increment
java
int a = 5;
System.out.println(a++); // Prints 5, THEN a becomes 6 (post-increment)
System.out.println(++a); // a becomes 7, THEN prints 7 (pre-increment)Relational (Comparison) Operators
Return true or false:
java
int x = 10, y = 20;
System.out.println(x == y); // false (equal to)
System.out.println(x != y); // true (not equal to)
System.out.println(x > y); // false (greater than)
System.out.println(x < y); // true (less than)
System.out.println(x >= 10); // true (greater than or equal)
System.out.println(x <= 5); // false (less than or equal)Logical Operators
Combine boolean expressions:
java
boolean a = true, b = false;
System.out.println(a && b); // false (AND — both must be true)
System.out.println(a || b); // true (OR — at least one true)
System.out.println(!a); // false (NOT — reverses)Short-Circuit Evaluation
Java uses short-circuit evaluation — it stops checking as soon as the result is determined:
java
// If first condition is false, second is NOT evaluated (&&)
if (x != 0 && 100 / x > 5) { ... }
// If first condition is true, second is NOT evaluated (||)
if (isAdmin || checkPermissions()) { ... }Assignment Operators
java
int x = 10; // Assign
x += 5; // x = x + 5 → 15
x -= 3; // x = x - 3 → 12
x *= 2; // x = x * 2 → 24
x /= 4; // x = x / 4 → 6
x %= 4; // x = x % 4 → 2Bitwise Operators
Operate on individual bits:
| Operator | Name | Example (5 & 3) |
|---|---|---|
& | AND | 0101 & 0011 = 0001 (1) |
| | OR | 0101 | 0011 = 0111 (7) |
^ | XOR | 0101 ^ 0011 = 0110 (6) |
~ | NOT | ~0101 = 1010 |
<< | Left Shift | 5 << 1 = 10 |
>> | Right Shift | 5 >> 1 = 2 |
Ternary Operator
Shorthand for simple if-else:
java
int age = 20;
String status = (age >= 18) ? "Adult" : "Minor";
System.out.println(status); // Adultinstanceof Operator
Checks if an object is an instance of a class:
java
String name = "Java";
System.out.println(name instanceof String); // true
System.out.println(name instanceof Object); // trueOperator Precedence
From highest to lowest:
| Priority | Operators |
|---|---|
| 1 | () (parentheses) |
| 2 | ++, --, !, ~ (unary) |
| 3 | *, /, % |
| 4 | +, - |
| 5 | <<, >>, >>> |
| 6 | <, <=, >, >=, instanceof |
| 7 | ==, != |
| 8 | &, ^, | |
| 9 | &&, || |
| 10 | ? : (ternary) |
| 11 | =, +=, -=, etc. |
Tip: When in doubt, use parentheses to make precedence explicit and code readable.
Practical Example
java
public class BillCalculator {
public static void main(String[] args) {
double subtotal = 1250.00;
double taxRate = 0.18;
double discount = (subtotal > 1000) ? 0.10 : 0.0;
double discountAmount = subtotal * discount;
double afterDiscount = subtotal - discountAmount;
double tax = afterDiscount * taxRate;
double total = afterDiscount + tax;
System.out.printf("Subtotal: ₹%.2f%n", subtotal);
System.out.printf("Discount: -₹%.2f (%.0f%%)%n", discountAmount, discount * 100);
System.out.printf("Tax: +₹%.2f (%.0f%% GST)%n", tax, taxRate * 100);
System.out.printf("Total: ₹%.2f%n", total);
}
}Output:
Subtotal: ₹1250.00
Discount: -₹125.00 (10%)
Tax: +₹202.50 (18% GST)
Total: ₹1327.50Summary
- Java provides arithmetic, relational, logical, bitwise, assignment, and ternary operators
++/--have pre and post forms with different evaluation order- Logical operators use short-circuit evaluation for efficiency
- Assignment operators (
+=,-=, etc.) combine operation with assignment - Use parentheses to clarify operator precedence
- The
instanceofoperator checks type compatibility at runtime