if-else Statement

The if-else statement in Java is a decision-making control structure used to execute one block of code when a condition is true and another block when it is false. It allows programs to handle two alternative execution paths. This concept is fundamental for real-time logic and interviews.

What Is the if-else Statement?

• Evaluates a boolean condition
• Executes if block when condition is true
• Executes else block when condition is false

Basic Syntax

if (condition) {
    // code if condition is true
} else {
    // code if condition is false
}
          

Simple Example

int number = 10;
if (number % 2 == 0) {
    System.out.println("Even number");
} else {
    System.out.println("Odd number");
}
          

Condition Rules

• Condition must return boolean
• Relational and logical expressions are commonly used
• Non-boolean conditions are not allowed

if (10 > 5) { }   // ✅ valid
if (10) { }       // ❌ invalid
          

if-else Without Braces

Braces {} can be omitted for single statements, but it is not recommended.

if (x > 0)
    System.out.println("Positive");
else
    System.out.println("Negative");
          

Best Practice: Always use braces to avoid logical errors.

if-else with Logical Operators

if (age >= 18 && hasId) {
    System.out.println("Access granted");
} else {
    System.out.println("Access denied");
}
          

Nested if-else

An if-else inside another if or else.

if (score >= 60) {
    if (score >= 90) {
        System.out.println("Grade A");
    } else {
        System.out.println("Grade B");
    }
} else {
    System.out.println("Fail");
}
          

if-else vs Ternary Operator

Using if-else

int max;
if (a > b) {
    max = a;
} else {
    max = b;
}
          

Using Ternary Operator

int max = (a > b) ? a : b;
          

Why it matters: Use ternary only for simple conditions.

Common Beginner Mistakes

• Using = instead of ==
• Forgetting braces
• Deep nesting reducing readability
• Using if-else for multiple conditions instead of else-if
• Writing complex logic inside conditions

Interview-Ready Answers

Short Answer

The if-else statement executes one block of code when a condition is true and another when it is false.

Detailed Answer

In Java, the if-else statement evaluates a boolean condition. If the condition is true, the if block is executed; otherwise, the else block is executed, allowing two alternative execution paths.

Key Takeaway

The if-else statement enables clear decision-making by handling true and false paths explicitly. Proper use improves code readability and correctness.