Brief Package Example

Bookpack:
The example creates a package called bookpack, which contains a simple class for managing a database of books.

Book Class:
It has private attributes title, author and pubDate (title, author and publication date).
Constructor method initializes attributes.
show() method displays the book details.

BookDemo Class:
Creates an array of 5 Book objects.
Populates the array with book information and displays the details using the show() method.

Code Example
Directory Structure:

src/
  bookpack/
    BookDemo.java

1. Defining the Book Class within the bookpack Package (bookpack/BookDemo.java):

// Demonstração breve dos pacotes.
package bookpack;

class Book {
    private String title;
    private String author;
    private int pubDate;

    // Construtor
    Book(String t, String a, int d) {
        title = t;
        author = a;
        pubDate = d;
    }

    // Método para exibir os detalhes do livro
    void show() {
        System.out.println(title);
        System.out.println(author);
        System.out.println(pubDate);
        System.out.println();
    }
}

// Classe para demonstrar o uso de Book
class BookDemo {
    public static void main(String args[]) {
        Book books[] = new Book[5];  // Cria uma matriz de objetos Book

        // Preenche a matriz com diferentes livros
        books[0] = new Book("Java: A Beginner's Guide", "Schildt", 2014);
        books[1] = new Book("Java: The Complete Reference", "Schildt", 2014);
        books[2] = new Book("The Art of Java", "Schildt and Holmes", 2003);
        books[3] = new Book("Red Storm Rising", "Clancy", 1986);
        books[4] = new Book("On the Road", "Kerouac", 1955);

        // Exibe os detalhes de cada livro
        for (int i = 0; i < books.length; i++) {
            books[i].show();
        }
    }
}

Compilation and Execution

1. Compiling the Code From the above bookpack directory, compile the file with:

javac bookpack/BookDemo.java

1. Running the Program Run the program from the current working directory with:

java bookpack.BookDemo

Important Explanations:

• Bookpack package: Both Book and BookDemo are part of the bookpack package. This means that to run the program, the package name must be specified.
• Run Command: When running BookDemo, the full package name is required (bookpack.BookDemo). Running java BookDemo without specifying the package will not work.

Expected Output:

Java: A Beginner's Guide
Schildt
2014

Java: The Complete Reference
Schildt
2014

The Art of Java
Schildt and Holmes
2003

Red Storm Rising
Clancy
1986

On the Road
Kerouac
1955

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