Java集合框架学习（六） LinkedList详解

LinkedList介绍

ArrayList与LinkedList都是List接口的实现类,因此都实现了List的所有未实现的方法,只是实现的方式有所不同。

LinkedList是采用链表的方式来实现List接口的,它本身有自己特定的方法，如: addFirst(),addLast(),getFirst(),removeFirst()等.。

由于是采用链表实现的,因此在进行insert和remove动作时在效率上要比ArrayList要好得多!适合用来实现Stack(堆栈)与

Queue(队列),前者先进后出，后者是先进先出。

public class LinkedList<E>
extends AbstractSequentialList<E>
implements List<E>, Deque<E>, Cloneable, Serializable

例子介绍

package com.dylan.collection;

import java.util.LinkedList;

/**
 * @author xusucheng
 * @create 2018-01-30
 **/
public class LinkedListExample {
    public static void main(String args[]) {

       /* Linked List Declaration */
        LinkedList<String> linkedlist = new LinkedList<String>();

       /*add(String Element) is used for adding
        * the elements to the linked list*/
        linkedlist.add("Item1");
        linkedlist.add("Item5");
        linkedlist.add("Item3");
        linkedlist.add("Item6");
        linkedlist.add("Item2");

       /*Display Linked List Content*/
        System.out.println("Linked List Content: " +linkedlist);

       /*Add First and Last Element*/
        linkedlist.addFirst("First Item");
        linkedlist.addLast("Last Item");
        System.out.println("LinkedList Content after addition: " +linkedlist);

       /*This is how to get and set Values*/
        Object firstvar = linkedlist.get(0);
        System.out.println("First element: " +firstvar);
        linkedlist.set(0, "Changed first item");
        Object firstvar2 = linkedlist.get(0);
        System.out.println("First element after update by set method: " +firstvar2);

       /*Remove first and last element*/
        linkedlist.removeFirst();
        linkedlist.removeLast();
        System.out.println("LinkedList after deletion of first and last element: " +linkedlist);

       /* Add to a Position and remove from a position*/
        linkedlist.add(0, "Newly added item");
        linkedlist.remove(2);
        System.out.println("Final Content: " +linkedlist);
    }
}

常用方法

增 : add, addAll, addFirst, addLast, push
删: clear, removeFirst, removeLast
改: set,
查: size, get, getFirst, getLast, indexOf, lastIndexOf, peek,
转换：toArray

如何遍历

1.For循环方式
2.高级For循环（foreach）
3.Iterator迭代器

4.While循环方式

package com.dylan.collection;

import java.util.Iterator;
import java.util.LinkedList;

/**
 * @author xusucheng
 * @create 2018-01-30
 **/
public class LinkedListLoopDemo {
    public static void main(String args[]) {
      /*LinkedList declaration*/
        LinkedList<String> linkedlist=new LinkedList<String>();
        linkedlist.add("Apple");
        linkedlist.add("Orange");
        linkedlist.add("Mango");

      /*for loop*/
        System.out.println("**For loop**");
        for(int num=0; num<linkedlist.size(); num++)
        {
            System.out.println(linkedlist.get(num));
        }

      /*Advanced for loop*/
        System.out.println("**Advanced For loop**");
        for(String str: linkedlist)
        {
            System.out.println(str);
        }

      /*Using Iterator*/
        System.out.println("**Iterator**");
        Iterator i = linkedlist.iterator();
        while (i.hasNext()) {
            System.out.println(i.next());
        }

      /* Using While Loop*/
        System.out.println("**While Loop**");
        int num = 0;
        while (linkedlist.size() > num) {
            System.out.println(linkedlist.get(num));
            num++;
        }

    }
}

模拟栈操作

package com.dylan.collection;

import java.util.LinkedList;

/**
 * @author xusucheng
 * @create 2018-01-30
 **/
public class LinkedListPushPopDemo {
    public static void main(String[] args) {

        // Create a LinkedList of Strings
        LinkedList<String> list = new LinkedList<String>();

        // Add few Elements
        list.add("Jack");
        list.add("Robert");
        list.add("Chaitanya");
        list.add("kate");

        // Display LinkList elements
        System.out.println("LinkedList contains: "+list);

        // push Element the list
        list.push("NEW ELEMENT");

        // Display after push operation
        System.out.println("LinkedList contains: "+list);
    }
}

转换LinkedList为ArrayList

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

public class ConvertExample {
 public static void main(String[] args) {
    LinkedList<String> linkedlist = new LinkedList<String>();
    linkedlist.add("Harry");
    linkedlist.add("Jack");
    linkedlist.add("Tim");
    linkedlist.add("Rick");
    linkedlist.add("Rock");

    List<String> list = new ArrayList<String>(linkedlist);

    for (String str : list){
      System.out.println(str);
    }
 }

}

转换LinkedList为Array

import java.util.LinkedList;

public class ConvertExample {
 public static void main(String[] args) {
 
    //Creating and populating LinkedList
    LinkedList<String> linkedlist = new LinkedList<String>();
    linkedlist.add("Harry");
    linkedlist.add("Maddy");
    linkedlist.add("Chetan");
    linkedlist.add("Chauhan");
    linkedlist.add("Singh");

    //Converting LinkedList to Array
    String[] array = linkedlist.toArray(new String[linkedlist.size()]);

    //Displaying Array content
    System.out.println("Array Elements:");
    for (int i = 0; i < array.length; i++)
    {
       System.out.println(array[i]);
    }
 }
}