Java/com/study/demo3/EBook.java

package com.study.demo3;

public class EBook extends Book {
  private double fileSize;

  public EBook() {
    super();
  }

  public EBook(String isbn, String title, double fileSize) {
    super(isbn, title);
    this.fileSize = fileSize;
  }

  public double getFileSize() {
    return fileSize;
  }

  public void setFileSize(double fileSize) {
    this.fileSize = fileSize;
  }

  @Override
  public String toString() {
    return "EBook [ISBN="
        + isbn
        + ", Title="
        + title
        + ", FileSize="
        + fileSize
        + "MB, Available="
        + available
        + "]";
  }
}