Unit 2 Lesson Hacks • 10 min read

Hack 1

import java.util.ArrayList;

public class ArrayListExample {
    private ArrayList<Integer> myArrayList = new ArrayList<>();

    public void addToArrayList(int value) {
        myArrayList.add(value);
    }

    public int getElementAtIndex(int index) {
        if (index >= 0 && index < myArrayList.size()) {
            return myArrayList.get(index);
        } else {
            throw new IndexOutOfBoundsException("Index is out of bounds.");
        }
    }

    public static void main(String[] args) {
        ArrayListExample example = new ArrayListExample();

        example.addToArrayList(10);
        example.addToArrayList(20);
        example.addToArrayList(30);

        int elementAtIndex = example.getElementAtIndex(1);
        System.out.println("Element at index 1: " + elementAtIndex);
    }
}
ArrayListExample.main(null)

Element at index 1: 20

Hack 2

import java.util.Random;
import java.util.Scanner;

public class SimpleMathGuessingGame {
    public static void main(String[] args) {
        Random random = new Random();
        int base = random.nextInt(9) + 2; // random base between 2 and 10 (inclusive)
        int exponent = random.nextInt(4) + 2; // random exponent between 2 and 5 (inclusive)
        double result = Math.pow(base, exponent);

        Scanner scanner = new Scanner(System.in);
        int attempts = 0;
        boolean guessed = false;

        System.out.println("Welcome to the Simple Math Guessing Game!");
        System.out.println("I have a number in mind, and you need to guess both the base and exponent.");

        while (!guessed) {
            System.out.print("Enter your guess for the base: ");
            int guessedBase = scanner.nextInt();

            System.out.print("Enter your guess for the exponent: ");
            int guessedExponent = scanner.nextInt();

            attempts++;

            if (guessedBase == base && guessedExponent == exponent) {
                guessed = true;
                System.out.println("Congratulations! You guessed it!");
                System.out.println("It took you " + attempts + " attempts.");
            } else {
                System.out.println("Sorry, that's not correct. Try again!");
            }
        }

        scanner.close();
    }
}
SimpleMathGuessingGame.main(null)

Welcome to the Simple Math Guessing Game!
I have a number in mind, and you need to guess both the base and exponent.
Enter your guess for the base: Enter your guess for the exponent: Sorry, that's not correct. Try again!
Enter your guess for the base: Enter your guess for the exponent: Sorry, that's not correct. Try again!
Enter your guess for the base: Enter your guess for the exponent: Sorry, that's not correct. Try again!
Enter your guess for the base: Enter your guess for the exponent: Sorry, that's not correct. Try again!
Enter your guess for the base: Enter your guess for the exponent: Sorry, that's not correct. Try again!
Enter your guess for the base: Enter your guess for the exponent: Sorry, that's not correct. Try again!
Enter your guess for the base: Enter your guess for the exponent: Sorry, that's not correct. Try again!
Enter your guess for the base: 

Hack 3

public class MyClass {
    private int intValue;
    private boolean boolValue;
    private String stringValue;
    private double doubleValue;

    public MyClass(int intValue, boolean boolValue, String stringValue, double doubleValue) {
        this.intValue = intValue;
        this.boolValue = boolValue;
        this.stringValue = stringValue;
        this.doubleValue = doubleValue;
    }

    public int getIntValue() {
        return intValue;
    }

    public boolean getBoolValue() {
        return boolValue;
    }

    public String getStringValue() {
        return stringValue;
    }

    public double getDoubleValue() {
        return doubleValue;
    }

    public static void main(String[] args) {
        MyClass myObject = new MyClass(42, true, "Hello, World!", 3.14);

        System.out.println("Int Value: " + myObject.getIntValue());
        System.out.println("Boolean Value: " + myObject.getBoolValue());
        System.out.println("String Value: " + myObject.getStringValue());
        System.out.println("Double Value: " + myObject.getDoubleValue());
    }
}
MyClass.main(null)

Int Value: 42
Boolean Value: true
String Value: Hello, World!
Double Value: 3.14

Hack 4

public class PersonName {
    private String fullName;

    public PersonName(String fullName) {
        this.fullName = fullName;
    }

    public String getFirstName() {
        int spaceIndex = fullName.indexOf(' ');
        if (spaceIndex != -1) {
            return fullName.substring(0, spaceIndex);
        } else {
            return fullName; 
        }
    }

    public String getLastName() {
        int spaceIndex = fullName.indexOf(' ');
        if (spaceIndex != -1) {
            return fullName.substring(spaceIndex + 1);
        } else {
            return ""; 
        }
    }

    public static void main(String[] args) {
        PersonName person = new PersonName("Parav Salaniwal");

        System.out.println("First Name: " + person.getFirstName()); 
        System.out.println("Last Name: " + person.getLastName());  
    }
}
PersonName.main(null)

First Name: Parav
Last Name: Salaniwal