Java Operators

Symbols that perform actions on values.

Arithmetic operators

Op	Meaning	Example	Result
`+`	Add	`5 + 3`	8
`-`	Subtract	`5 - 3`	2
`*`	Multiply	`5 * 3`	15
`/`	Divide	`10 / 3`	3 (int division!)
`%`	Modulo (remainder)	`10 % 3`	1

Integer division gotcha 10 / 3 with two ints gives 3, not 3.33. To get a decimal result, at least one operand must be a double: 10.0 / 3 gives 3.333....

Comparison operators

Return boolean:

Comparisons

int a = 5, b = 10;
System.out.println(a == b);   // false (equal)
System.out.println(a != b);   // true  (not equal)
System.out.println(a < b);    // true
System.out.println(a <= b);   // true
System.out.println(a > b);    // false
System.out.println(a >= b);   // false

String comparison: use .equals(), not == For strings, == compares references (memory addresses), not content. Always use .equals():

String a = "hello";
String b = new String("hello");
System.out.println(a == b);          // false
System.out.println(a.equals(b));     // true

Logical operators

Logical

boolean a = true, b = false;

System.out.println(a && b);   // false (AND)
System.out.println(a || b);   // true  (OR)
System.out.println(!a);        // false (NOT)

Short-circuit: && and || stop evaluating as soon as the result is determined. false && expensiveCheck() never calls expensiveCheck().

Assignment operators

Compound assignment

int x = 10;
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  → 2

Increment / decrement

++ and --

int i = 5;
i++;                        // post-increment: i is now 6
++i;                        // pre-increment:  i is now 7

int a = 5;
int b = a++;                // b = 5, then a = 6
int c = ++a;                // a = 7, then c = 7

Ternary operator

Compact if/else: condition ? valueIfTrue : valueIfFalse

Ternary

int age = 17;
String status = (age >= 18) ? "adult" : "minor";
System.out.println(status);  // "minor"

Bitwise operators

Operate on bits. Used in low-level code, flags, performance-critical paths.

Op	Meaning
`&`	Bitwise AND
`\|`	Bitwise OR
`^`	Bitwise XOR
`~`	Bitwise NOT
`<<`	Left shift (× 2)
`>>`	Right shift (÷ 2)

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