Type Casting and Operators

Operators let you perform calculations, comparisons, and logical operations. Type casting lets you convert a value from one data type to another when needed.

Arithmetic Operators

int a = 10, b = 3;
System.out.println(a + b);  // 13 — addition
System.out.println(a - b);  // 7  — subtraction
System.out.println(a * b);  // 30 — multiplication
System.out.println(a / b);  // 3  — integer division (drops decimal!)
System.out.println(a % b);  // 1  — modulus (remainder)

Watch out: dividing two ints always gives an int result — 10 / 3 is 3, not 3.33. To get a decimal, cast at least one operand to double: (double) a / b.

Relational and Logical Operators

Assignment Operators

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

Type Casting

Java supports two kinds of type conversion:

• Widening (implicit): smaller type → larger type — happens automatically, no data loss. int → long → float → double
• Narrowing (explicit): larger type → smaller type — must cast manually, can lose data

// Widening — automatic
int num = 100;
double d = num;          // 100.0, no cast needed

// Narrowing — explicit cast required
double price = 99.99;
int rounded = (int) price;   // 99 (truncated, NOT rounded)

Interview tip: (int) 9.9 gives 9, not 10 — narrowing casts truncate the decimal, they do not round to the nearest value.