Application Program Interface

Popcorn Hack 1

import java.util.ArrayList;

public class PopcornHack1 {
    public static void main(String[] args) {
        // Use Math.pow() to calculate 3^4
        double powerResult = Math.pow(3, 4);
        System.out.println("3^4 = " + powerResult);

        // Use Math.sqrt() to find the square root of 64
        double squareRootResult = Math.sqrt(64);
        System.out.println("√64 = " + squareRootResult);

        // Create an ArrayList of Strings
        ArrayList<String> colors = new ArrayList<>();

        // Add 3 colors ("red", "blue", "green")
        colors.add("red");
        colors.add("blue");
        colors.add("green");

        // Print the size of the ArrayList
        System.out.println("Number of colors in the list: " + colors.size());
    }
}

PopcornHack1.main(null);

3^4 = 81.0
√64 = 8.0
Number of colors in the list: 3

Popcorn Hack 2

public class Book {
    // Attributes
    String title;
    String author;
    int pages;

    // Constructor to set all attributes
    public Book(String title, String author, int pages) {
        this.title = title;
        this.author = author;
        this.pages = pages;
    }

    // displayInfo() method - prints all book info
    public void displayInfo() {
        System.out.println("Book Information:");
        System.out.println("Title: " + title);
        System.out.println("Author: " + author);
        System.out.println("Pages: " + pages);
    }

    // isLong() method - returns true if pages > 300
    public boolean isLong() {
        return pages > 300;
    }

    // Main method to test Book class
    public static void main(String[] args) {
        // Create a Book object
        Book myBook = new Book("Java Basics", "John Doe", 350);

        // Call displayInfo()
        myBook.displayInfo();

        // Call isLong() and print the result
        System.out.println("Is this book long? " + myBook.isLong());
    }
}
Book.main(null);

Book Information:
Title: Java Basics
Author: John Doe
Pages: 350
Is this book long? true

---

Homework Hack

import java.util.ArrayList;

// Phone Class
public class Phone {
    // Attributes
    String brand;
    String model;
    int batteryLevel;
    ArrayList<String> contacts;

    // Constructor - sets brand, model, and initializes battery and contacts list
    public Phone(String brand, String model) {
        this.brand = brand;
        this.model = model;
        this.batteryLevel = 100;           // starts at 100%
        this.contacts = new ArrayList<>(); // empty contact list
    }

    // displayInfo() - print phone info
    public void displayInfo() {
        System.out.println("Phone Info:");
        System.out.println("Brand: " + brand);
        System.out.println("Model: " + model);
        System.out.println("Battery Level: " + batteryLevel + "%");
    }

    // addContact(String name) - adds name to contacts
    public void addContact(String name) {
        contacts.add(name);
        System.out.println("👤 Contact added: " + name);
    }

    // showContacts() - print all contacts
    public void showContacts() {
        System.out.println("Contacts for " + brand + " " + model + ":");
        if (contacts.isEmpty()) {
            System.out.println("(No contacts saved)");
        } else {
            for (String contact : contacts) {
                System.out.println("- " + contact);
            }
        }
    }

    // usePhone(int minutes) - decrease battery
    public void usePhone(int minutes) {
        batteryLevel -= minutes;
        if (batteryLevel < 0) {
            batteryLevel = 0; // prevent negative battery
        }
        System.out.println("Used phone for " + minutes + " minutes. Battery now: " + batteryLevel + "%");
    }
}

// Phone Test Class
class PhoneTest {
    public static void main(String[] args) {
        // Create 2 Phone objects
        Phone phone1 = new Phone("Apple", "iPhone 15");
        Phone phone2 = new Phone("Samsung", "Galaxy S24");

        // Add 3 contacts to each phone
        phone1.addContact("Nolan");
        phone1.addContact("Yash");
        phone1.addContact("Yuva");

        phone2.addContact("Nora");
        phone2.addContact("Soni");
        phone2.addContact("Avika");

        System.out.println();

        // Use phones for some minutes
        phone1.usePhone(25);
        phone2.usePhone(40);

        System.out.println();

        // Display all information
        phone1.displayInfo();
        phone1.showContacts();

        System.out.println();

        phone2.displayInfo();
        phone2.showContacts();
    }
}

PhoneTest.main(null);

👤 Contact added: Nolan
👤 Contact added: Yash
👤 Contact added: Yuva
👤 Contact added: Nora
👤 Contact added: Soni
👤 Contact added: Avika

Used phone for 25 minutes. Battery now: 75%
Used phone for 40 minutes. Battery now: 60%

Phone Info:
Brand: Apple
Model: iPhone 15
Battery Level: 75%
Contacts for Apple iPhone 15:
- Nolan
- Yash
- Yuva

Phone Info:
Brand: Samsung
Model: Galaxy S24
Battery Level: 60%
Contacts for Samsung Galaxy S24:
- Nora
- Soni
- Avika