Java Operators Explained

When you're writing code in Java, you'll often need to do things like add two numbers, check if something is true, or assign a value to a variable. All of that is done using something called operators. Think of operators like special symbols or keywords that perform actions on values or variables.

1. Assignment Operator (=)

This is one of the first operators you'll use in Java. It’s used to assign values to variables.

int a = 10;

Here, you're saying "Hey Java, please put the value 10 into the variable a." This operator does not mean “equal to” like it does in math. It just means you’re storing something in a variable.

2. Arithmetic Operators

These are used to do basic math:

int x = 10, y = 3;
        System.out.println(x + y); // 13
        System.out.println(x - y); // 7
        System.out.println(x * y); // 30
        System.out.println(x / y); // 3
        System.out.println(x % y); // 1

Note: When dividing integers, Java gives you only the whole number part (no decimals). So 10 / 3 is 3, not 3.33.

3. Relational / Comparison Operators

These operators help you compare two values. They return either true or false.

int a = 5, b = 10;
        System.out.println(a == b); // false
        System.out.println(a != b); // true
        System.out.println(a < b);  // true

Important: == is used to compare values, not to assign. Beginners often confuse = and ==.

4. Logical Operators

Logical operators are used when dealing with multiple conditions.

int age = 20;
        boolean hasLicense = true;

        if (age >= 18 && hasLicense) {
            System.out.println("You can drive!");
        }

5. Unary Operators (++ and --)

These are used to increase or decrease a value by 1.

int a = 5;
        System.out.println(++a); // 6 (pre-increment)
        System.out.println(a++); // 6 (but a becomes 7 after this)

Tip: ++a changes the value before it’s used. a++ uses the value, then increases it.

6. Compound Assignment Operators (+=, -=, *=, /=, %=)

These are shortcuts for arithmetic combined with assignment.

int a = 5;
        a += 5; // same as a = a + 5;

7. Ternary Operator (? :)

This is like a shortcut for if-else. It takes three parts:

condition ? valueIfTrue : valueIfFalse;

int age = 16;
        String message = (age >= 18) ? "Adult" : "Minor";
        System.out.println(message); // Minor

8. Bitwise Operators

Used for bit-level operations, useful in low-level programming.

Official Java Documentation: Java Operators Documentation

Common Mistakes Beginners Make

Confusing = and ==

if (x = 5) // wrong! x = 5 is an assignment, not a comparison

Correct: if (x == 5)

Forgetting Integer Division

int result = 5 / 2;
System.out.println(result); // Output: 2, not 2.5

Use at least one double: double result = 5.0 / 2;

Misusing Logical Operators

if (a > 5 & b < 10) // works, but slower

Use && instead of & for efficiency.