Interpretation of Java documentation: Analysis of the addFirst() method function of the LinkedList class

Interpretation of Java documentation: functional analysis of the addFirst() method of the LinkedList class

LinkedList is a doubly linked list implementation class in the Java collection framework. It provides a series of Methods for adding, deleting, and searching in lists. Among them, the addFirst() method is one of the important methods in the LinkedList class. This article will provide an in-depth analysis of the functions of the addFirst() method, with specific code examples.

The function of the addFirst() method is very intuitive. Its function is to insert the specified element into the beginning of the linked list. This means that the element will become the first element in the linked list, and the original first element will become the second element. The declaration of the addFirst() method is as follows:

public void addFirst(E e)

It accepts a parameter e of type E, which represents the element to be inserted. The generic E here means that the linked list can store any type of object.

The following is a simple sample code that shows how to insert elements into a LinkedList using the addFirst() method:

import java.util.LinkedList;

public class LinkedListExample {
    public static void main(String[] args) {
        LinkedList<String> linkedList = new LinkedList<>();

        // 添加元素到链表的开头
        linkedList.addFirst("A");
        linkedList.addFirst("B");
        linkedList.addFirst("C");

        System.out.println(linkedList); // 输出：[C, B, A]
    }
}

In the above code, we create a LinkedList named linkedList object, and continuously calls the addFirst() method to insert three elements to the beginning of the linked list. Finally, we use the System.out.println() method to print the contents of the linked list, and the result is [C, B, A], which is the reverse order of our insertion.

It should be noted that the time complexity of the addFirst() method is O(1), that is, the time required for the insertion operation is fixed regardless of the size of the linked list. This is because in a doubly linked list, you only need to modify the pointer pointing, without traversing the entire linked list.

So far, we have analyzed the function of the addFirst() method and provided a simple code example. Through this method, we can easily insert elements into the beginning of LinkedList, allowing us to operate elements in the linked list more flexibly.

The above is the detailed content of Interpretation of Java documentation: Analysis of the addFirst() method function of the LinkedList class. For more information, please follow other related articles on the PHP Chinese website!