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Nested if

Learn nested if blocks.

Nested if

An if block can contain another if. This is called a nested if. The inner condition is only tested when the outer condition is also true.

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

Here the license is checked only when age is 18 or above. If age is younger, the inner block never runs. Nested if is used when multiple conditions must hold together.

A nested if example

A nested if can also be written with logical operators. The two snippets below are equivalent:

// Nested
if (age >= 18) {
    if (hasLicense) {
        System.out.println("Can drive");
    }
}
// Logical and
if (age >= 18 && hasLicense) {
    System.out.println("Can drive");
}

If two conditions can be simply AND-ed, prefer && over nesting. Nested if is more readable when the inner block has extra code or needs its own else.

Practice Weather advisor

Write a Main class with a main method. Assign 25 to int temp and false to boolean raining. Inside if (temp > 20) use if (!raining) to print System.out.println("Picnic").

Sample solution

Main.java
public class Main {
    public static void main(String[] args) {
        int temp = 25;
        boolean raining = false;
        if (temp > 20) {
            if (!raining) {
                System.out.println("Picnic");
            }
        }
    }
}

Expected output

Picnic

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 When does the inner block run in a nested if?

  • When outer is false
  • Only when inner is true
  • When outer is true and inner is true Correct answer
  • Always

Explanation: The inner block runs when both conditions are true.

2 Complete the nested condition

Question 
int age = 20;
boolean hasLicense = true;
if (age >= 18) {
    if (____) {
        System.out.println("Can drive");
    }
}
Answer 
int age = 20;
boolean hasLicense = true;
if (age >= 18) {
    if (hasLicense) {
        System.out.println("Can drive");
    }
}

Explanation: The inner condition checks hasLicense.

3 Match the nested if concepts

Term Meaning
if (a) Outer condition
if (b) Inner condition
&& Logical and
true && true Inner runs

All lessons in Beginner

1 Java basics

  1. What is Java?
  2. The main method
  3. Comments
  4. Class skeleton
  5. javac and java
  6. Summary - Java basics

2 Variables

  1. int and double
  2. boolean
  3. String
  4. Naming variables
  5. final variables
  6. Summary - Variables

3 Data types

  1. Primitive types
  2. Type casting
  3. String concatenation
  4. Math class
  5. BigInteger and BigDecimal
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add/subtract
  3. Multiply/divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic
  2. Comparison
  3. Logical
  4. Bitwise
  5. Assignment and increment
  6. Summary - Operators

6 String basics

  1. length and charAt
  2. equals and equalsIgnoreCase
  3. indexOf and substring
  4. toUpperCase and trim
  5. String.format
  6. Summary - String basics

7 Conditionals

  1. The if statement
  2. else and else if
  3. Nested if
  4. switch
  5. Ternary
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. do-while
  4. break and continue
  5. for-each
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Updating quantity
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. Filling arrays
  4. Multi-dimensional arrays
  5. Copying arrays
  6. Summary - Arrays

11 Array methods

  1. Arrays.sort
  2. Arrays.toString
  3. Arrays.binarySearch
  4. Arrays.copyOf
  5. Arrays.fill
  6. Summary - Array methods

12 Collections

  1. ArrayList
  2. add and get
  3. HashMap
  4. put and get
  5. HashSet
  6. Summary - Collections

13 Methods

  1. Defining methods
  2. return
  3. void methods
  4. Method overloading
  5. Scope
  6. Summary - Methods

14 Method parameters

  1. Primitive parameters
  2. Object parameters
  3. varargs
  4. Multiple values via array
  5. final parameters
  6. Summary - Method parameters

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 String builder

  1. StringBuilder
  2. append
  3. insert and delete
  4. reverse
  5. toString
  6. Summary - String builder

17 Input and output

  1. Scanner
  2. nextInt and nextLine
  3. System.out.printf
  4. BufferedReader
  5. try-with-resources
  6. Summary - Input and output

18 Enum

  1. Declaring enums
  2. values and valueOf
  3. Enum fields
  4. Enum methods
  5. switch with enum
  6. Summary - Enum

19 Exception basics

  1. try/catch
  2. finally
  3. throw
  4. Exception hierarchy
  5. Multiple catch
  6. Summary - Exception basics

20 Beginner final

  1. Project design
  2. Data model
  3. Business logic
  4. Error handling
  5. Putting it together