Java Operators

Operators in Java are symbols that perform actions on values and variables. They let you calculate numbers, store values, compare results, and combine true-or-false conditions.

You have already seen the assignment operator =, which stores a value in a variable. This lesson covers the operators beginners use most often in Java expressions.

Arithmetic Operators

Arithmetic operators work with numbers. They can add, subtract, multiply, divide, and find a remainder.

Operator	Meaning	Example
+	Addition	a + b
-	Subtraction	a - b
*	Multiplication	a * b
/	Division	a / b
%	Remainder	a % b

The remainder operator % gives what is left after division. For example, 17 % 5 gives 2 because 5 fits into 17 three times with 2 left over.

Example

public class Main {
    public static void main(String[] args) {
        int a = 17;
        int b = 5;

        System.out.println("Sum: " + (a + b));
        System.out.println("Difference: " + (a - b));
        System.out.println("Product: " + (a * b));
        System.out.println("Integer division: " + (a / b));
        System.out.println("Remainder: " + (a % b));
    }
}

Output:

Sum: 22
Difference: 12
Product: 85
Integer division: 3
Remainder: 2

How It Works

The variables a and b are both int values. Because both sides of a / b are integers, Java performs integer division and removes the decimal part. The result is 3, not 3.4.

If you need a decimal result, use a decimal type such as double. For example, dividing 17.0 by 5.0 would produce 3.4.

Assignment Operators

The assignment operator = stores a value in a variable. Java also has compound assignment operators that update a variable using its current value.

Operator	Example	Same As
+=	x += 3	x = x + 3
-=	x -= 3	x = x - 3
*=	x *= 3	x = x * 3
/=	x /= 3	x = x / 3
%=	x %= 3	x = x % 3

These operators are common when a value changes step by step, such as adding points to a score or reducing a count.

Comparison Operators

Comparison operators test two values and produce a boolean result: true or false.

Operator	Meaning
==	Equal to
!=	Not equal to
>	Greater than
<	Less than
>=	Greater than or equal to
<=	Less than or equal to

Use == when comparing values. A single = assigns a value instead of checking equality.

Logical Operators

Logical operators combine or change boolean expressions. && means both conditions must be true, || means at least one condition must be true, and ! means not.

public class Main {
    public static void main(String[] args) {
        int score = 85;
        int attempts = 2;

        boolean passed = score >= 70;
        boolean canRetry = attempts < 3;
        boolean needsHelp = score < 60 || attempts >= 3;

        score += 5;

        System.out.println("Passed: " + passed);
        System.out.println("Can retry: " + canRetry);
        System.out.println("Needs help: " + needsHelp);
        System.out.println("Updated score: " + score);
    }
}

Output:

Passed: true
Can retry: true
Needs help: false
Updated score: 90

The expression score >= 70 is true because 85 is greater than or equal to 70. The expression score < 60 || attempts >= 3 is false because neither condition is true.

Increment And Decrement

Java also has shortcuts for adding or subtracting exactly 1. The operator ++ increases a variable by one, and -- decreases a variable by one.

public class Main {
    public static void main(String[] args) {
        int lives = 3;

        lives--;
        System.out.println("After losing one: " + lives);

        lives++;
        System.out.println("After gaining one: " + lives);
    }
}

Output:

After losing one: 2
After gaining one: 3

Common Mistakes

• Using = when you meant == in a comparison.
• Expecting integer division to keep the decimal part.
• Using % when you need normal division instead of the remainder.
• Forgetting that && requires both conditions to be true.

Takeaway: operators are the building blocks of Java expressions, and the type of each value affects the result you get.