list方法在java中的工作原理 [英] How list methods works in java

问题描述

List是java中的一个接口。它有一些方法。通常，接口是方法原型的规范。即接口由方法签名组成，只有接口中的方法不存在实现。

List is an interface in java. And it has some methods. Generally an interface is a specification of method prototypes. i.e. interface consist of methods signature only no implementation will be there for that methods in interface.

我怀疑如果List接口的方法在接口中没有任何实现，List接口的方法是如何工作的。

I have a doubt that how the methods of List interface work if they don't have any implementation inside the interface.

假设我有一个具有name属性，setter，getter方法的类Book。
我还有另一个类getBooks。

Suppose I have a class Book which has name property, setter,getter methods. and I have another class getBooks like this.

public class GetBooks{
List<Book> list;
public List<Book> getBooks(){
return list;
}
//setter method..
}

I我正在运行时通过其他类将书籍发送到set方法。

I am sending books into the set method at runtime through some other class.

我有另一个类UseBooks就是这样。

I have another class UseBooks like this.

public class UseBooks{
.....
....
List<Book> list = new GetBooks().getBooks();
list.add(new Book("aaa"));
}

我的问题是add方法是如何添加书籍的，即使它在接口列表中也是如此我的getBooks（）返回List接口而不是Arraylist或其他一些实现类。

My question is how add method is adding books even it is in interface List because my getBooks() returning List interface not Arraylist or some other implementation class.

推荐答案

Java provides 3 concrete classes which implement the list interface
Vector
ArrayList
LinkedList

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