another example of static

Book.java
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public class Book {
    private static int idCount = 0;
    private int id;
    private String name;
    private String author;
    private int pageCount;

    public Book(String name, String author, int pageCount){
        this.name = name;
        this.author = author;
        this.pageCount = pageCount;
        this.id = idCount;
        idCount += 1;
    }

    @Override
    public String toString() {
        return String.format("id: %d, name: %s, author: %s, number of pages: %d",id ,name, author, pageCount);
    }

    public static int getBookCount(){
        return idCount;
    }
}


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Tester.java
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public class Tester {
    public static void main(String[] args){
        Book b1 = new Book("Book1", "Author1", 10000);
        Book b2 = new Book("Book2", "Author2", 25);
        Book b3 = new Book("Book3", "Author2", 25);
        Book b4 = new Book("Book4", "Author2", 25);
        Book b5 = new Book("Book5", "Author2", 25);

        System.out.println(b1);
        System.out.println(b5);
        System.out.println(b3);
        System.out.println(b4);
        System.out.println(b2);

        System.out.println("the total number of book is: "+Book.getBookCount());

    }
}