Java - Operators

Operators

Arithmetic

int a = 5 + 2; int b = a - 3; int c = a * b; int d = a / b; int r = a % b;

Integer division truncates toward zero. Use double for floating-point division.

Comparison

boolean ok = (a > 3) && (a < 10);

Logical

&& and || short-circuit; & and | always evaluate both operands.

Bitwise and Shift

int flags = 0b0101;
int setMask = 0b0010;
flags |= setMask;   // set bit
boolean isSet = (flags & setMask) != 0;
int shifted = flags << 1;

Assignment and Compound

int x = 0; x += 5; x *= 2;

Equality: == vs equals()

== compares primitives by value and references by identity. For strings and most objects, use equals().

String s1 = new String("hi");
String s2 = new String("hi");
boolean sameRef = (s1 == s2);       // false
boolean sameVal = s1.equals(s2);    // true

Precedence and Associativity

When in doubt, add parentheses to make intent explicit.

int v = 1 + 2 * 3;    // 7 (multiplication before addition)
int w = (1 + 2) * 3;  // 9

Numeric Promotion

Mixed-type arithmetic promotes smaller types to larger (e.g., int to long, long to double).

Try it

1. Evaluate 1 + 2 * 3 vs (1 + 2) * 3 and explain precedence.
2. Use == vs equals() on two distinct but equal strings.
3. Manipulate bit flags: set, clear, and toggle a bit.