Master Core Java Programming From Scratch

What is an Operator?

An operator is a symbol that tells Java to perform an operation on one or more values or variables.

int a = 10;

int b = 5;

int result = a + b;

Here, + is the arithmetic operator.

Types of Operators

1. Arithmetic Operators

Arithmetic operators are used to perform mathematical calculations.

int a = 20;

int b = 6;

System.out.println(a + b);

System.out.println(a - b);

System.out.println(a * b);

System.out.println(a / b);

System.out.println(a % b);

Addition with Strings

The + operator also performs string concatenation when one operand is a String.

String name = "CIIT Institute 🤓 ";

int startingYear = 2014;

System.out.println(name + " Established in " + startingYear);

Output:

CIIT Institute 🤓 Established in 2014

2. Unary Operators

Unary operators operate on a single operand.

int count = 10;

count++;

System.out.println(count);

count--;

System.out.println(count);

Pre-Increment and Post-Increment

The position of ++ determines whether the value is incremented before or after its current value is used.

int a = 5;

int x = ++a;

System.out.println(a);

System.out.println(x);

In pre-increment, the variable is incremented before the value is assigned to x.

int b = 5;

int y = b++;

System.out.println(b);

System.out.println(y);

In post-increment, the current value is used first and then the variable is incremented.

3. Relational Operators

Relational operators compare two values and produce a boolean result.

int age = 25;

System.out.println(age >= 18);

System.out.println(age == 25);

System.out.println(age < 18);

== with Objects and Strings

For primitive values, == compares values. For object references, == checks whether two references refer to the same object.

To compare String contents, use equals().

String a = new String("CIIT");

String b = new String("CIIT");

System.out.println(a == b);

System.out.println(a.equals(b));

4. Logical Operators

Logical operators combine boolean expressions.

int age = 25;

boolean hasId = true;

boolean eligible = age >= 18 && hasId;

System.out.println(eligible);

Short-Circuit Evaluation

Java's && and || operators use short-circuit evaluation.

With &&, if the first condition is false, the remaining conditions may not be evaluated. With ||, if the first condition is true, the remaining conditions may not be evaluated.

int age = 15;

if (age >= 18 && age <= 60) {

    System.out.println("Eligible");

}

5. Assignment Operators

Assignment operators assign values to variables.

int value = 10;

value += 5;

value *= 2;

System.out.println(value);

6. Bitwise Operators

Bitwise operators operate on the individual bits of integral values.

int a = 5;

int b = 3;

System.out.println(a & b);

System.out.println(a | b);

System.out.println(a ^ b);

System.out.println(~a);

7. Shift Operators

Shift operators move the bits of an integral value.

int number = 8;

System.out.println(number << 1);

System.out.println(number >> 1);

8. Ternary Operator

The ternary operator is a compact conditional expression with three operands.

int age = 20;

String result = age >= 18 ? "Adult" : "Minor";

System.out.println(result);

Syntax:

condition ? valueIfTrue : valueIfFalse

Operator Precedence

When an expression contains multiple operators, Java follows defined precedence and associativity rules.

int result = 10 + 5 * 2;

System.out.println(result);

Multiplication has higher precedence than addition, so the multiplication is evaluated first.

Use parentheses when you want the evaluation order to be explicit.

int result = (10 + 5) * 2;

System.out.println(result);

Complete Example

public class Operators {

    public static void main(String[] args) {

        int marks = 85;

        int bonus = 5;

        int total = marks + bonus;

        boolean passed = total >= 40;

        String result = passed ? "Pass" : "Fail";

        System.out.println("Total: " + total);

        System.out.println("Result: " + result);

    }

}

Operator Best Practices

• Use parentheses when an expression could be difficult to understand.
• Avoid unnecessarily complex expressions.
• Remember that integer division discards the fractional part.
• Use equals() for String content comparison.
• Use short-circuit operators when appropriate for boolean conditions.
• Be careful with overflow when performing arithmetic on fixed-width integer types.