Java Operator Fundamentals — Quick & Clear

Short examples and outputs to make operators easy for students.

1. Precedence & Associativity

Operator precedence determines the order in which operators are evaluated. Associativity decides evaluation direction when precedence is same.

Example: multiplication has higher precedence than addition.

int x = 10 + 5 * 2;
System.out.println(x); // multiplication first
    

Assignment stores a value into a variable. Right-hand side is evaluated first, then assigned to the left-hand variable.

int a = 10;
int b = a + 5;
System.out.println(b);
    

Use +, -, *, /, % for arithmetic on numbers.

int a = 10, b = 3;
System.out.println(a + b);
System.out.println(a % b);
    

13
1

Prefix (++x) updates the value then uses it. Postfix (x++) uses the current value then updates it.

int x = 5;
System.out.println(++x); // 6
System.out.println(x++); // 6 (old value)
System.out.println(x);   // 7 (after postfix)
    

6
6
7

Short form of if-else: condition ? valueIfTrue : valueIfFalse. Great for concise expressions.

int age = 20;
String res = (age >= 18) ? "Adult" : "Minor";
System.out.println(res);
    

Adult

Compare values using >, <, >=, <=, ==, !=. They return boolean results.

int a = 10, b = 20;
System.out.println(a < b); // true
    

true

Use && (AND), || (OR), and ! (NOT) to combine boolean expressions.

boolean x = true, y = false;
System.out.println(x && y);
System.out.println(x || y);
    

false
true

Operate at bit-level: &, |, ^, ~, shifts <<, >>. Useful in low-level tasks and optimizations.

int x = 5;  // 0101
int y = 3;  // 0011
System.out.println(x & y); // 0001 -> 1
System.out.println(x | y); // 0111 -> 7
    

1
7

High to low (short): () → ++/-- → * / % → + - → << >> → & → ^ → | → && → || → ?: → = =

1️⃣ Which operator has higher precedence: * or +?

The multiplication operator (*) has higher precedence.

2️⃣ What does a = b + 5 do?

It evaluates b + 5 first, then assigns the result to a.

3️⃣ What is the % operator?

The modulus operator; it returns the remainder after division.

4️⃣ If x = 5, what is the output of ++x?

It outputs 6 because prefix increments before use.

5️⃣ Write a ternary expression to check if x is positive.

String r = (x > 0) ? "Positive" : "Not Positive";

6️⃣ What does == check for primitives?

It checks if the two primitive values are equal.

7️⃣ What is the result of true && false?

It evaluates to false.

8️⃣ What is the bitwise result of 5 & 3?

Binary: 0101 & 0011 = 0001 → 1.

9️⃣ Explain postfix x++ behavior.

It returns the current value of x, then increments x by 1.

🔟 Which operator short-circuits: && or &?

The conditional && short-circuits (doesn't evaluate right-hand side if left is false); bitwise & always evaluates both sides.