用Java编程定义一个Book类可以从键盘输入书名和价格并能根据价格进行比较。创建一个泛型集合存放图书，对图书进行排序并输出。

好的，以下是Java代码实现：

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;

public class Book implements Comparable<Book> {
    private String title;
    private double price;

    public Book(String title, double price) {
        this.title = title;
        this.price = price;
    }

    public String getTitle() {
        return title;
    }

    public double getPrice() {
        return price;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public int compareTo(Book book) {
        if (this.price > book.price) {
            return 1;
        } else if (this.price < book.price) {
            return -1;
        } else {
            return 0;
        }
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        ArrayList<Book> books = new ArrayList<>();

        System.out.println("Please enter the number of books: ");
        int num = scanner.nextInt();
        scanner.nextLine();

        for (int i = 0; i < num; i++) {
            System.out.println("Please enter the title of book " + (i + 1) + ": ");
            String title = scanner.nextLine();
            System.out.println("Please enter the price of book " + (i + 1) + ": ");
            double price = scanner.nextDouble();
            scanner.nextLine();
            books.add(new Book(title, price));
        }

        Collections.sort(books);
        System.out.println("Sorted by price (ascending order):");
        for (Book book : books) {
            System.out.println(book.getTitle() + " - $" + book.getPrice());
        }

        Collections.sort(books, new Comparator<Book>() {
            @Override
            public int compare(Book book1, Book book2) {
                return book2.getTitle().compareTo(book1.getTitle());
            }
        });
        System.out.println("\nSorted by title (descending order):");
        for (Book book : books) {
            System.out.println(book.getTitle() + " - $" + book.getPrice());
        }
    }
}

在这个例子中，我们首先在`main`方法中使用`Scanner`从键盘输入要创建的书籍数量，并使用循环逐个输入每个书籍的标题和价格。然后，我们将每个`Book`对象添加到`ArrayList`中。

接下来，我们使用`Collections.sort`方法对图书进行排序。在第一次排序中，我们使用默认的价格比较方法来对图书进行排序（升序）。在第二次排序中，我们使用自定义的标题比较方法对图书进行排序（降序）。最后，我们打印出每个图书的标题和价格来验证排序是否正确。