Question

You are going to model a Book in a library. The Book class should contain a title and an author (exactly 1 author is OK). Also, a book can be checked out and returned by a student. A Book object should be able to identify the student who currently holds the book.

1.Design the public interface (public constructor and public methods) for a class Book. You can use String to represent title, author, and student.

2. Implement the class Book (instance variables and constructor+method bodies) from the previous question.

3.Suppose the library also has other items that can be checked out (e.g., DVDs). Thus we introduce a base class for all items that can be checked out.

public class LibraryItem { ... }

and thus Book can inherit from LibraryItem.

public class Book extends LibraryItem { ... }

Which of the methods of Book's public interface would you move to LibraryItem's public interface?

4.

Extend the Book class and implement a method
boolean equals(Object o) { /* YOUR CODE */ }

that tests whether a book has the same title and author than some other Book.

Answer 1

Below are the required classes for the given problem:

LibraryItem.java:

public class LibraryItem {

private String student, returnDate;

private boolean isCheckedOut;

public String getStudent() {

return student;

}

public void setStudent(String student) {

this.student = student;

}

public String getReturnDate() {

return returnDate;

}

public void setReturnDate(String returnDate) {

this.returnDate = returnDate;

}

public boolean isCheckedOut() {

return isCheckedOut;

}

public void setCheckedOut(boolean isCheckedOut) {

this.isCheckedOut = isCheckedOut;

}

}

Book.java:

public class Book extends LibraryItem{

private String title,author;

public Book(String title,String author) {

this.title = title;

this.author = author;

}

public String getTitle() {

return title;

}

public void setTitle(String title) {

this.title = title;

}

public String getAuthor() {

return author;

}

public void setAuthor(String author) {

this.author = author;

}

//equals to find whether a book has the same title and author than some other Book

@Override

public boolean equals(Object obj) {

//if obj is instance of Book then only we can compare the author and title

if(obj instanceof Book) {

Book temp = (Book)obj;

if(this.title.equals(temp.getTitle()) && this.author.equals(temp.getAuthor())){

return true;

}

}

return false;

}

}