Java Programming · Week 3

If Statements

Step 1 of 5

Java Guided Tutorials - Conditionals

What You'll Learn

Welcome to our Java Conditionals Tutorial! In this lesson, you'll learn about conditional statements in Java, which allow your programs to make decisions and execute different code based on certain conditions.

Lesson Overview:

Introduction to Conditionals in Java
Working with Nested If Statements
Using Logical Operators in Conditions
Weekly Project: Applying Conditionals

By the end of this lesson, you'll be able to use if-else statements, nested conditionals, and logical operators to create more complex and dynamic Java programs.

1. Introduction to Conditionals in Java

If-Else Statements

Conditionals in Java allow you to execute certain blocks of code depending on whether a boolean condition is true or false. The most basic form is the if-else statement.

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

Let's practice with a simple grade calculator:

Try it Yourself

Complete the GradeCalculator program below. Use if-else statements to assign the correct grade based on the score.

Starter code

public class GradeCalculator {
    public static void main(String[] args) {
        int score = 70;
        char grade;

        // Your code here
        // Use if-else statements to determine the grade
        // A: 90-100, B: 80-89, C: 70-79, D: 60-69, F: 0-59

        System.out.println(grade);
    }
}

Write your code here

Make it print C

Did it work?

Your program should print this:

Paste what you got:

2. Working with Nested If Statements in Java

Nested Conditionals

Nested if statements allow you to check multiple conditions in a more complex decision-making process. It's an if statement inside another if or else block.

if (outerCondition) {
    if (innerCondition) {
        // code to execute if both conditions are true
    } else {
        // code to execute if outer is true but inner is false
    }
} else {
    // code to execute if outer condition is false
}

Try it Yourself

Complete the MovieTicketPrice program. Use nested if statements to determine the ticket price based on age and whether it's a weekend.

Starter code

public class MovieTicketPrice {
    public static void main(String[] args) {
        int age = 20;
        boolean isWeekend = true;
        double ticketPrice;

        // Your code here
        // Use nested if statements to determine the ticket price
        // Adult (18+) weekend price: $15, weekday price: $12
        // Child (<18) weekend price: $10, weekday price: $8

        System.out.println("Ticket Price: " + ticketPrice);
    }
}

Write your code here

Make it print Ticket Price: 15.0

Did it work?

Your program should print this:

Ticket Price: 15.0

Paste what you got:

3. Using Logical Operators in Java

Combining Conditions

Logical operators in Java allow you to combine multiple conditions in a single statement. The main logical operators are:

AND (&&): Both conditions must be true
OR (||): At least one condition must be true
NOT (!): Inverts the boolean value

if (condition1 && condition2) {
    // Execute if both conditions are true
} else if (condition3 || condition4) {
    // Execute if either condition is true
} else if (!condition5) {
    // Execute if condition5 is false
}

Try it Yourself

Complete the DiscountEligibility program. Use logical operators to determine if a person is eligible for a discount based on their age and membership status.

Starter code

public class DiscountEligibility {
    public static void main(String[] args) {
        int age = 30;
        boolean isMember = false;
        boolean eligibleForDiscount;

        // Your code here
        // Use logical operators to determine discount eligibility
        // Eligible if: (age >= 60 OR isMember == true) AND age >= 18

        System.out.println("Eligible for Discount: " + eligibleForDiscount);
    }
}

Write your code here

Make it print Eligible for Discount: false

Did it work?

Your program should print this:

Eligible for Discount: false

Paste what you got:

4. Weekly Project: Decision Maker

Project Description

Create a Java program that helps a user make a decision based on multiple inputs. This project will incorporate all the conditional concepts you've learned.

Requirements:

Use at least one if-else statement
Include a nested if statement
Use logical operators to combine conditions
Provide at least three different possible outcomes

Example idea: Create a program that suggests a mode of transportation based on distance, weather, and time constraints.

Implement the TransportationAdvisor program. Use the online compiler below to write and test your code. Once you're satisfied with your program, paste the output in the autograder to check your work.

Starter code

public class TransportationAdvisor {
    public static void main(String[] args) {
        int distance = 5; // in kilometers
        boolean isRaining = true;
        int availableTime = 30; // in minutes

        String suggestedTransportation;

        // Your code here
        // Use if-else statements, nested ifs, and logical operators
        // to determine the suggested mode of transportation
        // Options: "Walk", "Bike", "Take the bus", "Drive a car"

        System.out.println("Suggested transportation: " + suggestedTransportation);
    }
}

Write your code here

Make it print Suggested transportation: Take the bus

Did it work?

Your program should print this:

Suggested transportation: Take the bus

Paste what you got:

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