Java Nested If - Syntax, Examples and Explanation

⏱️ 7 min read • Beginner Level • Lesson 24

Lesson 24 of 124 of Java Tutorial

A nested if statement in Java means writing one if statement inside another if or else block. It is used when one condition should be checked only after another condition is true.

Before learning nested if, you should understand Java if statement, Java if-else statement, and Java if-else-if ladder.

On this page:

What is Nested If?
Syntax of Nested If
Flowchart of Nested If
How does Nested If work?
Nested If Example
Program Explanation
Login Validation Example
Nested If vs If-Else-If
Common Mistakes
Summary

What is Nested If in Java?

A nested if statement is an if statement placed inside another if statement. The inner condition is checked only when the outer condition is true.

Nested if is useful when a condition depends on another condition.
The inner if block executes only if the outer condition is true.
Nested if can be used with if, if-else, and else blocks.

Syntax of Nested If Statement

The syntax of nested if contains one if statement inside another if block.

NestedIfSyntax.java

Copy Download

if (condition1) {
    // executes when condition1 is true

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

Note: The inner if condition is checked only when the outer if condition is true.

Flowchart of Nested If

Execution flow of a nested if statement

How does Nested If work?

Java first checks the outer if condition.
If the outer condition is false, the inner condition is not checked.
If the outer condition is true, Java enters the outer block.
Then Java checks the inner if condition.
If the inner condition is also true, the inner block executes.

Nested If Example in Java

The following program checks whether a number is a natural number. If it is greater than 0, then it checks whether the number is even or odd.

NestedIfExample.java

Copy Try Download

import java.util.Scanner;

public class NestedIfExample {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter any number: ");
        int x = sc.nextInt();

        if (x > 0) {
            if (x % 2 == 0) {
                System.out.println("X is EVEN");
            } else {
                System.out.println("X is ODD");
            }
        } else {
            System.out.println("Not a Natural Number");
        }

        sc.close();
    }
}

Sample Input 1:

Output 1:

Enter any number:12 
X is EVEN

Sample Input 2:

Output 2:

Enter any number:3 
X is ODD

Sample Input 3:

-12

Output 3:

Enter any number:-12
Not a Natural Number

Explanation of the Program

The program imports the Scanner class to read input from the keyboard.
A Scanner object named sc is created.
The user enters a number, and it is stored in variable x.
The outer condition x > 0 checks whether the number is natural.
If x > 0 is true, the inner condition x % 2 == 0 is checked.
If the inner condition is true, the program prints X is EVEN.
If the inner condition is false, the program prints X is ODD.
If the outer condition is false, the program prints Not a Natural Number.
The Scanner object is closed using sc.close().

This example checks username first. If the username is correct, then it checks the password. This is a good real-life use case of nested if.

LoginValidationExample.java

Copy Try Download

public class LoginValidationExample {
    public static void main(String[] args) {
        String username = "admin";
        String password = "12345";

        if (username.equals("admin")) {
            if (password.equals("12345")) {
                System.out.println("Login Successful");
            } else {
                System.out.println("Incorrect Password");
            }
        } else {
            System.out.println("Invalid Username");
        }
    }
}

Output:

Login Successful

Explanation of Login Validation Program

The program stores username as "admin".
The program stores password as "12345".
The outer if checks whether the username is correct.
If the username is correct, the inner if checks the password.
If both username and password are correct, the program prints Login Successful.
If the username is correct but password is wrong, it prints Incorrect Password.
If the username itself is wrong, it prints Invalid Username.

Difference Between Nested If and If-Else-If Ladder

Nested If	If-Else-If Ladder
One condition is checked inside another condition.	Multiple conditions are checked one by one.
Useful when one condition depends on another.	Useful when there are multiple independent choices.
Can become harder to read if deeply nested.	Usually easier to read for multiple related conditions.
Example: login username then password check.	Example: grade calculation based on marks.

Common Mistakes in Nested If

Writing too many nested levels, making the code hard to read.
Forgetting braces { }, especially when nesting conditions.
Using = instead of == for comparison.
Using == instead of equals() for comparing strings.
Checking an inner condition that should be checked independently.

Best Practice: If your nested if code becomes too deep, consider using logical operators, if-else-if ladder, or separate methods to make the code cleaner.

Summary:

Nested if means placing one if statement inside another.
The inner condition is checked only if the outer condition is true.
Nested if is useful when one condition depends on another condition.
It is commonly used in validation, login checks, and multi-step decision-making.
Avoid too much nesting because it can make code hard to read.

Frequently Asked Questions

Nested if in Java means writing one if statement inside another if or else block.

Nested if should be used when one condition should be checked only after another condition is true.

Java first checks the outer if condition. If it is true, then the inner if condition is checked. If the outer condition is false, the inner condition is skipped.

Yes, Java allows if, if-else, and else-if blocks to be written inside another if or else block.

Nested if checks one condition inside another condition, while an if-else-if ladder checks multiple conditions one by one.

Nested if is useful, but too much nesting can make code hard to read. For complex logic, use cleaner conditions or separate methods.

Next step: Learn Java Switch Case

🚀 Continue to Java Switch Case →

🧠 Test your understanding with a quick quiz

🚀 Quick Knowledge Check

Topic: Nested-if | Language: Java

Q1. What will be the output?

String username = "admin";
String password = "12345";

if (username.equals("admin")) {
    if (password.equals("12345")) {
        System.out.println("Login Successful");
    } else {
        System.out.println("Incorrect Password");
    }
} else {
    System.out.println("Invalid Username");
}

Q2. When is the inner if condition checked in nested if?

Q3. What will be the output of this code?

int x = -5;
if (x > 0) {
    if (x % 2 == 0) {
        System.out.println("Even");
    } else {
        System.out.println("Odd");
    }
} else {
    System.out.println("Not Natural");
}

Q4. Which of the following is a good use case for nested if?

Q5. Which statement is true about nested if?

Q6. What is a common problem with too many nested if statements?

Q7. What will be the output of this code?

int x = 12;
if (x > 0) {
    if (x % 2 == 0) {
        System.out.println("Even");
    } else {
        System.out.println("Odd");
    }
} else {
    System.out.println("Not Natural");
}

Q8. Which method should be used to compare strings in nested if conditions?

String username = "admin";
if (username.____("admin")) { }

Q9. What is the main difference between nested if and if-else-if ladder?

Q10. What is nested if in Java?

🎉 Great job! Continue learning Java step by step.

Java Else If Ladder

Java Switch Statement