Java operators and expression evaluation order

Operators and Precedence

Operators control how values combine. Precedence controls which operation runs first when you mix them.

Arithmetic

int a = 10, b = 3;
System.out.println(a + b);   // 13
System.out.println(a - b);   // 7
System.out.println(a * b);   // 30
System.out.println(a / b);   // 3  ← integer division, remainder dropped
System.out.println(a % b);   // 1  ← modulus (remainder)

Integer division truncates — 10 / 3 is 3, not 3.33. Cast to double first: (double) a / b.

Comparison and Logical

boolean result = (a > 5) && (b < 5);  // true
boolean either = (a > 20) || (b < 5); // true
boolean not    = !(a == 10);           // false

Short-circuit evaluation: In &&, if the left side is false, the right side never evaluates. In ||, if the left is true, the right is skipped. This matters when the right side has a side effect or null check.

Compound Assignment

int x = 5;
x += 3;  // x = 8
x *= 2;  // x = 16
x++;     // x = 17  (post-increment)
++x;     // x = 18  (pre-increment)

Use parentheses to override default precedence whenever the order is non-obvious. Explicit grouping prevents bugs and aids readability.