用集合做参数:先在main方法中,创建book对象,放进接口之后,接口作为参数进行传递,对person对象进行初始化.
Book类:

package com.qf.demo4;


public class Book {  

    private String bookName;
    private double price;
    private String author;
    public Book(String bookName, double price, String author) {
        super();
        this.bookName = bookName;
        this.price = price;
        this.author = author;
    }
    public Book() {
        super();
    }
    public String getBookName() {
        return bookName;
    }
    public void setBookName(String bookName) {
        this.bookName = bookName;
    }
    public double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
    public String getAuthor() {
        return author;
    }
    public void setAuthor(String author) {
        this.author = author;
    }
    @Override
    public String toString() {
        return "Book [bookName=" + bookName + ", price=" + price + ", author=" + author + "]";
    }
}

Person类
注意:类的属性定义为接口,如何初始化person对象的.

package com.qf.demo4;
import java.util.ArrayList;
public class Person {
    private String name;
    private int age;
    private ArrayList<Book> books;
    public Person(String name, int age, ArrayList<Book> books) {
        super();
        this.name = name;
        this.age = age;
        this.books = books;
    }
    public Person() {
        super();
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public ArrayList<Book> getBooks() {
        return books;
    }
    public void setBooks(ArrayList<Book> books) {
        this.books = books;
    }
    @Override
    public String toString() {
        return "Person [name=" + name + ", age=" + age + ", books=" + books + "]";
    }
}

main方法:

package com.qf.demo4;
/**
 * 集合  本身也是一个对象
 * 可以作为 属性   参数     实际参数 传递
 * debug  
 *          1  先确定要 检测的部分, 添加断点 
 *          2  用debug模式进行 运行
 * 
 * Ctrl + shif + i 得到选中的语句的  结果
 * 
 * F5 进入指定的方法
 * F6 下一行
 * F8 下一个断点
 */
import java.util.ArrayList;

public class Test {

    public static void main(String[] args) {
        ArrayList<Book> books = new ArrayList<>();
        books.add(new Book("java编程思想", 108, "二狗"));
        books.add(new Book("java从入门到放弃", 1008, "康帅傅"));
        
        Person person =new Person("小香菇", 18, books);
        System.out.println(person);
        
        
        Person person2 = new Person();
        System.out.println(person2);
        
        person2.setName("皮皮虾");
        person2.setAge(18);
        System.out.println(person2);
        // 必须 给  books 集合 初始化
        person2.setBooks(books);
        
        String author  = person2.getBooks().get(0).getAuthor();
        System.out.println(author);
        
        int w = 5;
        int i = w+7+w+4+7;
        
    }
    
    public static void  test(){
        System.out.println("abc");
    }
}