Nested If

1. Introduction

In Java, nested if statements allow you to place one if (or else) statement inside another.
They help in writing multi-level decision-making logic where one condition depends on another.

Nested if is useful when:

• Multiple conditions must be checked in sequence
• One condition should be evaluated only if another is true
• You need structured, hierarchical decision logic
• Handling real-world workflows (authentication → role validation → permissions, etc.)

2. What Is a Nested If?

A nested if means one if statement inside another:

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

Flow:

1. Check condition1
2. If true → check condition2
3. If both are true → inner block executes

3. Basic Example

int age = 20;
boolean hasId = true;

if (age >= 18) {
    if (hasId) {
        System.out.println("Entry Allowed");
    }
}

Output:

Entry Allowed

Explanation:

• First condition: age >= 18 → true
• Second condition: hasId → true
• Both true → message prints

4. Nested If…Else Example

int marks = 85;

if (marks >= 40) {
    if (marks >= 75) {
        System.out.println("Distinction");
    } else {
        System.out.println("Pass");
    }
} else {
    System.out.println("Fail");
}

Output:

Distinction

Why?

• Marks >= 40 → true
• Marks >= 75 → true → Distinction

5. Multi-Level Nested If Example

You can nest multiple levels, though it affects readability.

int year = 2024;
boolean hasPassport = true;
boolean hasVisa = true;

if (hasPassport) {
    if (hasVisa) {
        if (year >= 2023) {
            System.out.println("Travel Approved");
        }
    }
}

Output:

Travel Approved

6. Nested If with Range Checks

int score = 92;

if (score >= 0 && score <= 100) {
    if (score >= 90) {
        System.out.println("Grade A");
    } else if (score >= 75) {
        System.out.println("Grade B");
    } else if (score >= 60) {
        System.out.println("Grade C");
    } else {
        System.out.println("Grade D");
    }
} else {
    System.out.println("Invalid Score");
}

7. Real-World Example: Login + Role

Common scenario: first verify login, then check role.

boolean loggedIn = true;
String role = "admin";

if (loggedIn) {
    if (role.equals("admin")) {
        System.out.println("Welcome Admin");
    } else {
        System.out.println("Welcome User");
    }
} else {
    System.out.println("Please log in first");
}

8. When to Use Nested If

Use nested if when:

• You need to verify conditions in order
• One condition depends on another
• Logic becomes incorrect if conditions are flattened
• You want structured validation (e.g., form validation)

Example:

1. Check if form submitted
2. Check if fields are valid
3. Check if user exists
4. Check if payment is approved

9. When Not to Use Nested If

Avoid nested if when:

• Logic becomes too deep and confusing
• Multiple independent conditions exist → use else if chain
• Switch-case is more readable
• You can simplify with logical operators (&&, ||)

Bad example (too deep):

if (a) {
    if (b) {
        if (c) {
            if (d) {
                // complex logic
            }
        }
    }
}

Better rewritten using &&:

if (a && b && c && d) {
    // logic
}

10. Summary

• Nested if means placing one if inside another.
• Used for multi-level decision-making.
• Inner condition executes only when outer condition is true.
• Useful for structured workflows like login, validation, grading, etc.
• Avoid overly deep nested structures—rewrite using &&, ||, or switch when possible.

Written By: Shiva Srivastava