引用传递

范例应用一对一对应关系
class Person{
    private Book book ;
    private String name ;
    private int age ;
    public Person(String name,int age){
        this.name = name ;
        this.age = age ;
    }
    public void setName(String name){
        this.name = name ;
    }
    public void setAge(int age){
        this.age = age ;    
    }
    public String getName(){
        return name ;
    }
    public int getAge(){
        return age ;
    }
    public void setBook(Book book){
        this.book = book ;
    }
    public Book getBook(){
        return book ;
    }
    
}
class Book{
    private Person person ;
    private float price ;
    private String name ;
    public Book(String name,float price){
        this.name = name ;
        this.price = price ;
    }
    public void setName(String name){
        this.name = name ;
    }
    public void setPrice(float price){
        this.price = price ;    
    }
    public String getName(){
        return name ;
    }
    public float getPrice(){
        return price ;
    }
    public void setPerson(Person person){
        this.person = person ;
    }
    public Person getPerson(){
        return person ;
    }
}
public class PreDemo01{
    public static void main(String [] args){
        Person per = null ;
        Book book = null ;
        per = new Person("张三",33) ;
        book = new Book("爸爸去哪儿",12.8f) ;
        per.setBook(book) ;
        String a = per.getName() ;
        System.out.print(a) ;
        System.out.print("******************************我是分割线*******************" ) ;
        System.out.println("现在我们就可以看出属性之间的一一对应关系-->"+per.getName()
            +"的年龄是"+per.getAge()+"他喜欢看"+per.getBook().getName()
            +",这本书的价格是"+per.getBook().getPrice()) ;
        book.setPerson(per) ;
        System.out.print(book.getName()+"-->"+book.getPrice()+"-->"+book.getPerson().getName()+"-->"
                    +book.getPerson().getAge()) ;
    }    
}