🍿 Popcorn Hack #1: Using Documentation (5 minutes)

Task: Use the Math class and ArrayList class based on their documentation.

Complete the following:

  1. Use Math.pow() to calculate 3^4
  2. Use Math.sqrt() to find square root of 64
  3. Create an ArrayList of Strings
  4. Add 3 colors to the ArrayList
  5. Print the ArrayList size
// Popcorn Hack #1: Complete this code

import java.util.ArrayList;

public class PopcornHack1 {
    public static void main(String[] args) {

        // TODO: Use Math.pow() to calculate 3^4
        System.out.println("3 to the power of 4: " + Math.pow(3, 4));
        
        // TODO: Use Math.sqrt() to find square root of 64
        System.out.println("Square root of 64: " + Math.sqrt(64));
        
        // TODO: Create ArrayList of Strings
        ArrayList<String> colors = new ArrayList<>();
        
        // TODO: Add 3 colors ("red", "blue", "green")
        colors.add("red");
        colors.add("blue");
        colors.add("green");
        
        // TODO: Print the size
        System.out.println("Number of colors: " + colors.size());
        
    }
}

PopcornHack1.main(null);

3 to the power of 4: 81.0
Square root of 64: 8.0
Number of colors: 3

🍿 Popcorn Hack #2: Attributes and Behaviors (5 minutes)

Task: Create a Book class with attributes and behaviors.

Requirements:

Attributes (3):

  • title (String)
  • author (String)
  • pages (int)

Behaviors (3 methods):

  1. Constructor to set all attributes
  2. displayInfo() - print all book info
  3. isLong() - return true if pages > 300

Test: Create a Book object and call all methods.

// Popcorn Hack #2: Complete the Book class

public class Book {

    // TODO: Add 3 attributes (title, author, pages)
    private String title;
    private String author;
    private int pages;
    
    // TODO: Add constructor
    public Book(String title, String author, int pages) {
        this.title = title;
        this.author = author;
        this.pages = pages;
    }
    
    // TODO: Add displayInfo() method
    public void displayInfo() {
        System.out.println("Title: " + title);
        System.out.println("Author: " + author);
        System.out.println("Pages: " + pages);
    }
    
    // TODO: Add isLong() method (returns true if pages > 300)
    public boolean isLong() {
        return pages > 300;
    }
    
}

// Create a Book object and test all methods
Book myBook = new Book("Java Basics", "Nolan Hightower", 5678);

// Test the methods
myBook.displayInfo();
System.out.println("Is it a long book? " + myBook.isLong());


Title: Java Basics
Author: Nolan Hightower
Pages: 5678
Is it a long book? true
Author: Nolan Hightower
Pages: 5678
Is it a long book? true

📝 Homework Hack: Phone Class

Create a Phone class that demonstrates all concepts from this lesson:

  • Libraries/Classes
  • Packages (use ArrayList from java.util)
  • Attributes
  • Behaviors

Requirements:

Attributes (4):

  • brand (String)
  • model (String)
  • batteryLevel (int) - starts at 100
  • contacts (ArrayList)

Behaviors (5 methods):

  1. Constructor - sets brand and model, initializes empty contacts list
  2. displayInfo() - prints brand, model, and battery level
  3. addContact(String name) - adds name to contacts list
  4. showContacts() - prints all contacts
  5. usePhone(int minutes) - decreases battery by minutes used

Testing:

  • Create 2 Phone objects
  • Add 3 contacts to each phone
  • Use phone for some minutes
  • Display all information

Grading:

  • Correct attributes (4 points)
  • Correct methods (5 points)
  • Proper use of ArrayList from java.util (3 points)
  • Complete testing (3 points)
  • Total: 15 points
// Homework Hack: Complete the Phone class


import java.util.ArrayList;

public class Phone {
    // TODO: Add 4 attributes
    private String brand;
    private String model;
    private int batteryLevel;
    private ArrayList<String> contacts;
    
    // TODO: Add constructor
    public Phone(String brand, String model) {
        this.brand = brand;
        this.model = model;
        this.batteryLevel = 100; // starts at 100
        this.contacts = new ArrayList<>();
    }
    
    // TODO: Add displayInfo() method
    public void displayInfo() {
        System.out.println("Brand: " + brand);
        System.out.println("Model: " + model);
        System.out.println("Battery Level: " + batteryLevel + "%");
    }
    
    // TODO: Add addContact(String name) method
    public void addContact(String name) {
        contacts.add(name);
    }
    
    // TODO: Add showContacts() method
    public void showContacts() {
        System.out.println("Contacts:");
        for (String contact : contacts) {
            System.out.println("- " + contact);
        }
    }
    
    // TODO: Add usePhone(int minutes) method
    public void usePhone(int minutes) {
        batteryLevel -= minutes;
        if (batteryLevel < 0) {
            batteryLevel = 0;
        }
    }
}

// Test your Phone class
public class PhoneTest {
    public static void main(String[] args) {
        // TODO: Create 2 Phone objects
        Phone phone1 = new Phone("Apple", "iPhone 14");
        Phone phone2 = new Phone("Samsung", "Galaxy S23");
        
        // TODO: Add 3 contacts to each
        phone1.addContact("Alice");
        phone1.addContact("Bob");
        phone1.addContact("Charlie");

        phone2.addContact("David");
        phone2.addContact("Eve");
        phone2.addContact("Frank");
        
        // TODO: Use phones for some minutes
        phone1.usePhone(30);
        phone2.usePhone(45);
        
        // TODO: Display all information
        phone1.displayInfo();
        phone1.showContacts();
        phone2.displayInfo();
        phone2.showContacts();
        
    }
}

PhoneTest.main(null);

Brand: Apple
Model: iPhone 14
Battery Level: 70%
Contacts:
- Alice
- Bob
- Charlie
Brand: Samsung
Model: Galaxy S23
Battery Level: 55%
Contacts:
- David
- Eve
- Frank