Nested if Statement

A nested if statement is an if statement inside another if or else block. It is used when one condition depends on another condition and decisions must be made in a hierarchical or step-by-step manner. This concept is important for business rules, validations, and interviews.

What Is a Nested if Statement?

• An if inside another if or else
• Inner condition is evaluated only if the outer condition is true
• Used for dependent conditions

Basic Syntax

if (condition1) {
    if (condition2) {
        // code if both conditions are true
    }
}
          

Simple Example

int age = 20;
boolean hasLicense = true;
if (age >= 18) {
    if (hasLicense) {
        System.out.println("Eligible to drive");
    }
}
          

Why it matters: hasLicense is checked only if age condition passes.

Nested if with else

int marks = 75;
if (marks >= 40) {
    if (marks >= 90) {
        System.out.println("Grade A");
    } else {
        System.out.println("Grade B");
    }
} else {
    System.out.println("Fail");
}
          

Real-Time Example (Business Logic)

if (isUserLoggedIn) {
    if (hasPremiumAccess) {
        showPremiumContent();
    } else {
        showBasicContent();
    }
}
          

Nested if vs Logical Operators

Nested if

if (age >= 18) {
    if (hasId) {
        allowEntry();
    }
}
          

Using Logical Operator (&&)

if (age >= 18 && hasId) {
    allowEntry();
}
          

Best Practice: Use logical operators when conditions are independent.

else Binding Rule (Important Interview Trap)

In nested if, else always binds to the nearest unmatched if.

if (a > b)
    if (a > c)
        System.out.println("A is largest");
    else
        System.out.println("C is largest");
          

Best Practice: Always use braces {}.

When to Use Nested if

• Conditions are dependent
• Step-by-step validation
• Multi-level business rules

When to Avoid Nested if

• Deep nesting reduces readability
• Can often be replaced with:
  • Logical operators
  • else-if ladder
  • switch statement

Common Beginner Mistakes

• Missing braces
• Excessive nesting
• Confusing else binding
• Using nested if for independent conditions

Interview-Ready Answers

Short Answer

A nested if statement is an if inside another if or else block, used for dependent conditions.

Detailed Answer

In Java, nested if statements allow checking multiple conditions in a hierarchical manner. The inner if is evaluated only when the outer condition is true, making it suitable for step-by-step decision-making.

Key Takeaway

Nested if statements are powerful for dependent logic, but should be used carefully to maintain readability and avoid logical confusion.