Testing

public class Book {
    
    protected String title;
    static int count = 0;
    protected double startTime;

    public Book(String title) {
        this.title = title;
        this.startTime = System.nanoTime();
        count++;
    }

    public String toString() {
        return "Title: " + title;
    }

    public int getBookCount() {
        return count;
    }

    public double shelfLife() {
        return (System.nanoTime() - startTime);
    }

    public boolean readyToRemove() {
        return (this.shelfLife() > 2 * 1000000000);
    }
}

class Novel extends Book {

    private String author;
    private int checkouts;

    Novel(String title, String author) {
        super(title);
        this.author = author;
        this.checkouts = 0;
    }

    Novel(String title) {
        this(title, "Unknown");
    }

    @Override
    public String toString() {
        return "Title: " + title + " by " + author;
    }

    public String getAuthor() {
        return this.author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public void checkout() {
        checkouts++;
        this.startTime = System.nanoTime();

    }

    public int getCheckouts() {
        return this.checkouts;
    }


}

class Textbook extends Book {

    private String publishingCompany;

    Textbook(String title, String publishingCompany) {
        super(title);
        this.publishingCompany = publishingCompany;
    }

    Textbook(String title) {
        this(title, "Unknown");
    }

    public String getPublishingCompany() {
        return this.publishingCompany;
    }

    public void setPublishingCompany(String publishingCompany) {
        this.publishingCompany = publishingCompany;
    }

    @Override
    public String toString() {
        return "Title: " + title + " by " + publishingCompany;
    }

}

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

        System.out.println("---------------------------------------------------");
        System.out.println("Part 1:");

        Book[] books1 = {
                        new Book("Crime and Punishment"),
                        new Book("Lord of the Flies"),
                        new Book("Big Bird"),
                        new Book("The Great Gatsby")
                    };

        for (Book b : books1) {
            System.out.println(b);
            System.out.println("ID: " + b.hashCode());
        }

        System.out.println();
        System.out.println("Book Count: " + Book.count);


        System.out.println("---------------------------------------------------");
        System.out.println("Part 2:");

        Novel[] novels1 = {
            new Novel("The Scarlett Letter", "Nathaniel Hawthorne"),
            new Novel("Brave New World"),
        };

        Textbook[] textbooks1 = {
            new Textbook("AP Calculus BC", "College Board"),
            new Textbook("Java for Dummies")
        };

        novels1[1].setAuthor("Aldous Huxley");
        textbooks1[1].setPublishingCompany("John Doe");

        for (Novel b : novels1) {
            System.out.println(b);
            System.out.println("ID: " + b.hashCode());
            System.out.println("Shelf Life: " + b.shelfLife());
        }

        for (Textbook b : textbooks1) {
            System.out.println(b);
            System.out.println("ID: " + b.hashCode());
            System.out.println("Shelf Life: " + b.shelfLife());
        }


        System.out.println("---------------------------------------------------");
        System.out.println("Part 3:");
        
        Novel n1 = new Novel("The Hobbit");
        Novel n2 = new Novel("The Lord of the Rings");

        Textbook t1 = new Textbook("AP Physics C: Mechanics");
        Textbook t2 = new Textbook("AP Physics C: Electricity and Magnetism");

        System.out.println("Is n1 ready to remove? " + n1.readyToRemove());
        System.out.println("Is n2 ready to remove? " + n2.readyToRemove());

        System.out.println("Is t1 ready to remove? " + t1.readyToRemove());
        System.out.println("Is t2 ready to remove? " + t2.readyToRemove());

        try {
            Thread.sleep(3000);
          } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
          }

        n1.checkout();

        System.out.println("Is n1 ready to remove? " + n1.readyToRemove());
        System.out.println("Is n2 ready to remove? " + n2.readyToRemove());

        System.out.println("Is t1 ready to remove? " + t1.readyToRemove());
        System.out.println("Is t2 ready to remove? " + t2.readyToRemove());


    }
}

Tester.main(null);

---------------------------------------------------
Part 1:
Title: Crime and Punishment
ID: 1709604710
Title: Lord of the Flies
ID: 12540617
Title: Big Bird
ID: 671513864
Title: The Great Gatsby
ID: 682198516

Book Count: 4
---------------------------------------------------
Part 2:
Title: The Scarlett Letter by Nathaniel Hawthorne
ID: 2128794312
Shelf Life: 600125.0
Title: Brave New World by Aldous Huxley
ID: 2078725461
Shelf Life: 2394375.0
Title: AP Calculus BC by College Board
ID: 335166579
Shelf Life: 3148667.0
Title: Java for Dummies by John Doe
ID: 448014109
Shelf Life: 3786292.0
---------------------------------------------------
Part 3:
Is n1 ready to remove? false
Is n2 ready to remove? false
Is t1 ready to remove? false
Is t2 ready to remove? false
Is n1 ready to remove? false
Is n2 ready to remove? true
Is t1 ready to remove? true
Is t2 ready to remove? true

public class Wowza {

    public void do(int[] arr) {
        arr = {0,0,0,0};
    }

    public void print() {
        int[] arr = {9,9,9,9};
        do(arr);
        for (int num : arr) {
            System.out.println(num);
        }
    }

    public static void main(String[] args) {
        print();
    }
}