LinkedList的基本使用

LinkedList类是双向列表,列表中的每个节点都包含了对前一个和后一个元素的引用.

LinkedList的构造函数如下

1. public LinkedList(): ——生成空的链表

2. public LinkedList(Collection col): 复制构造函数

1、获取链表的第一个和最后一个元素

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import java.util.LinkedList;

public class LinkedListTest{

public static void main(String[] args) {

LinkedList lList = new LinkedList();

lList.add(“1”);

lList.add(“2”);

lList.add(“3”);

lList.add(“4”);

lList.add(“5”);

System.out.println("链表的第一个元素是 : " + lList.getFirst());
System.out.println("链表最后一个元素是 : " + lList.getLast());

}

}

2、获取链表元素

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for (String str: lList) {

System.out.println(str);

}

3、从链表生成子表

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List subl = lList.subList(1, 4);

System.out.println(subl);

lst.remove(2);

System.out.println(lst);

System.out.println(lList);

4、添加元素：添加单个元素

如果不指定索引的话，元素将被添加到链表的最后.

public boolean add(Object element)

public boolean add(int index, Object element)

也可以把链表当初栈或者队列来处理:

public boolean addFirst(Object element)

public boolean addLast(Object element)

addLast()方法和不带索引的add()方法实现的效果一样.

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import java.util.LinkedList;

public class LinkedListTest{

public static void main(String[] a) {

LinkedList list = new LinkedList();

list.add(“A”);

list.add(“B”);

list.add(“C”);

list.add(“D”);

list.addFirst(“X”);

list.addLast(“Z”);

System.out.println(list);

}

}

5、删除元素

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public Object removeFirst()

public Object removeLast()

import java.util.LinkedList;

public class MainClass {

public static void main(String[] a) {

LinkedList list = new LinkedList();
list.add("A");
list.add("B");
list.add("C");
list.add("D");
list.removeFirst();
list.removeLast();
System.out.println(list);

}

}

6、使用链表实现栈效果

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import java.util.LinkedList;

public class MainClass {

public static void main(String[] args) {

StackL stack = new StackL();

for (int i = 0; i < 10; i++)

stack.push(i);

System.out.println(stack.top());

System.out.println(stack.top());

System.out.println(stack.pop());

System.out.println(stack.pop());

System.out.println(stack.pop());

}

}

class StackL {

private LinkedList list = new LinkedList();

public void push(Object v) {

list.addFirst(v);

}

public Object top() {

return list.getFirst();

}

public Object pop() {

return list.removeFirst();

}

}

7、使用链表来实现队列效果

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import java.util.LinkedList;

public class MainClass {

public static void main(String[] args) {

Queue queue = new Queue();

for (int i = 0; i < 10; i++)

queue.put(Integer.toString(i));

while (!queue.isEmpty())

System.out.println(queue.get());

}

}

class Queue {

private LinkedList list = new LinkedList();

public void put(Object v) {

list.addFirst(v);

}

public Object get() {

return list.removeLast();

}

public boolean isEmpty() {

return list.isEmpty();

}

}

8、将LinkedList转换成ArrayList

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ArrayList arrayList = new ArrayList(linkedList);

for (String s : arrayList) {

System.out.println(“s = ” + s);

}

9、删掉所有元素：清空LinkedList

lList.clear();

10、删除列表的首位元素

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import java.util.LinkedList;

public class Main {

public static void main(String[] args) {

LinkedList lList = new LinkedList();

lList.add(“1”);

lList.add(“2”);

lList.add(“3”);

lList.add(“4”);

lList.add(“5”);

System.out.println(lList);

//元素在删除的时候，仍然可以获取到元素

Object object = lList.removeFirst();

System.out.println(object + ” has been removed”);

System.out.println(lList);

object = lList.removeLast();

System.out.println(object + ” has been removed”);

System.out.println(lList);

}

}

11、根据范围删除列表元素

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import java.util.LinkedList;

public class Main {

public static void main(String[] args) {

LinkedList lList = new LinkedList();

lList.add(“1”);

lList.add(“2”);

lList.add(“3”);

lList.add(“4”);

lList.add(“5”);

System.out.println(lList);

lList.subList(2, 5).clear();

System.out.println(lList);

}

}

12、删除链表的特定元素

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import java.util.LinkedList;

public class Main {

public static void main(String[] args) {

LinkedList lList = new LinkedList();

lList.add(“1”);

lList.add(“2”);

lList.add(“3”);

lList.add(“4”);

lList.add(“5”);

System.out.println(lList);

System.out.println(lList.remove(“2”));//删除元素值=2的元素

System.out.println(lList);

Object obj = lList.remove(2); //删除第二个元素

System.out.println(obj + ” 已经从链表删除”);

System.out.println(lList);

}

}

13、将LinkedList转换为数组，数组长度为0

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import java.util.LinkedList;

import java.util.List;

public class Main {

public static void main(String[] args) {

List theList = new LinkedList();

theList.add(“A”);

theList.add(“B”);

theList.add(“C”);

theList.add(“D”);

String[] my = theList.toArray(new String[0]);

for (int i = 0; i < my.length; i++) {

System.out.println(my[i]);

}

}

}

14、将LinkedList转换为数组，数组长度为链表长度

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import java.util.LinkedList;

import java.util.List;

public class Main {

public static void main(String[] args) {

List theList = new LinkedList();

theList.add(“A”);

theList.add(“B”);

theList.add(“C”);

theList.add(“D”);

String[] my = theList.toArray(new String[theList.size()]);

for (int i = 0; i < my.length; i++) {

System.out.println(my[i]);

}

}

}

15、将LinkedList转换成ArrayList

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import java.util.ArrayList;

import java.util.LinkedList;

import java.util.List;

public class Main {

public static void main(String[] args) {

LinkedList myQueue = new LinkedList();

myQueue.add(“A”);

myQueue.add(“B”);

myQueue.add(“C”);

myQueue.add(“D”);

List myList = new ArrayList(myQueue);

for (Object theFruit : myList)

System.out.println(theFruit);

}

}

16、实现栈

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import java.util.Collections;

import java.util.LinkedList;

public class Main {

public static void main(String[] argv) throws Exception {

LinkedList stack = new LinkedList();

Object object = “”;

stack.addFirst(object);

Object o = stack.getFirst();

stack = (LinkedList) Collections.synchronizedList(stack);

}

}

17、实现队列

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import java.util.LinkedList;

public class Main {

public static void main(String[] argv) throws Exception {

LinkedList queue = new LinkedList();

Object object = “”;

// Add to end of queue

queue.add(object);

// Get head of queue

Object o = queue.removeFirst();

}

}

18 、同步方法

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import java.util.Collections;

import java.util.LinkedList;

public class Main {

public static void main(String[] argv) throws Exception {

LinkedList queue = new LinkedList();

Object object = “”;

queue.add(object);

Object o = queue.removeFirst();

queue = (LinkedList) Collections.synchronizedList(queue);

}

}

19、查找元素位置

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import java.util.LinkedList;

public class Main {

public static void main(String[] args) {

LinkedList lList = new LinkedList();

lList.add(“1”);

lList.add(“2”);

lList.add(“3”);

lList.add(“4”);

lList.add(“5”);

lList.add(“2”);

System.out.println(lList.indexOf(“2”));

System.out.println(lList.lastIndexOf(“2”));

}

}

20、替换元素

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import java.util.LinkedList;

public class Main {

public static void main(String[] args) {

LinkedList lList = new LinkedList();

lList.add(“1”);

lList.add(“2”);

lList.add(“3”);

lList.add(“4”);

lList.add(“5”);

System.out.println(lList);

lList.set(3, “Replaced”);//使用set方法替换元素，方法的第一个参数是元素索引，后一个是替换值

System.out.println(lList);

}

}

21、链表添加对象

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import java.util.LinkedList;

class Address {

private String name;

private String street;

private String city;

private String state;

private String code;

Address(String n, String s, String c, String st, String cd) {

name = n;

street = s;

city = c;

state = st;

code = cd;

}

public String toString() {

return name + ” ” + street + ” ” + city + ” ” + state + ” ” + code;

}

}

class MailList {

public static void main(String args[]) {

LinkedList
ml = new LinkedList();

ml.add(new Address(“A”, “11 Ave”, “U”, “IL”, “11111”));

ml.add(new Address(“R”, “11 Lane”, “M”, “IL”, “22222”));

ml.add(new Address(“T”, “8 St”, “C”, “IL”, “33333”));

for (Address element : ml)

System.out.println(element + “\n”);

}

}

22、确认链表是否存在特定元素

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import java.util.LinkedList;

public class Main {

public static void main(String[] args) {

LinkedList lList = new LinkedList();

lList.add(“1”);

lList.add(“2”);

lList.add(“3”);

lList.add(“4”);

lList.add(“5”);

if (lList.contains(“4”)) {

System.out.println(“LinkedList contains 4”);

} else {

System.out.println(“LinkedList does not contain 4”);

}

}

}

23、根据链表元素生成对象数组

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Object[] objArray = lList.toArray();

for (Object obj: objArray) {

System.out.println(obj);

}

24、链表多线程

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import java.util.Collections;

import java.util.LinkedList;

import java.util.List;

class PrepareProduction implements Runnable {

private final List queue;

PrepareProduction(List q) {

queue = q;

}

public void run() {

queue.add(“1”);

queue.add(“done”);

}

}

class DoProduction implements Runnable {

private final List queue;

DoProduction(List q) {

queue = q;

}

public void run() {

String value = queue.remove(0);

while (!value.equals(“*”)) {

System.out.println(value);

value = queue.remove(0);

}

}

}

public class Main {

public static void main(String[] args) throws Exception {

List q = Collections.synchronizedList(new LinkedList());

Thread p1 = new Thread(new PrepareProduction(q));

Thread c1 = new Thread(new DoProduction(q));

p1.start();

c1.start();

p1.join();

c1.join();

}

}

25、优先级链表（来自JBOSS）

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import java.util.ArrayList;

import java.util.LinkedList;

import java.util.List;

import java.util.ListIterator;

import java.util.NoSuchElementException;

public class BasicPriorityLinkedList {

protected LinkedList[] linkedLists;

protected int priorities;

protected int size;

public BasicPriorityLinkedList(int priorities) {

this.priorities = priorities;

initDeques();

}

public void addFirst(Object obj, int priority) {

linkedLists[priority].addFirst(obj);

size++;

}

public void addLast(Object obj, int priority) {

linkedLists[priority].addLast(obj);

size++;

}

public Object removeFirst() {

Object obj = null;

for (int i = priorities - 1; i >= 0; i–) {

LinkedList ll = linkedLists[i];

if (!ll.isEmpty()) {

obj = ll.removeFirst();

break;

}

}

if (obj != null) {

size–;

}

return obj;

}

public Object removeLast() {

Object obj = null;

for (int i = 0; i < priorities; i++) {

LinkedList ll = linkedLists[i];

if (!ll.isEmpty()) {

obj = ll.removeLast();

}

if (obj != null) {

break;

}

}

if (obj != null) {

size–;

}

return obj;

}

public Object peekFirst() {

Object obj = null;

for (int i = priorities - 1; i >= 0; i–) {

LinkedList ll = linkedLists[i];

if (!ll.isEmpty()) {

obj = ll.getFirst();

}

if (obj != null) {

break;

}

}

return obj;

}

public List getAll() {

List all = new ArrayList();

for (int i = priorities - 1; i >= 0; i–) {

LinkedList deque = linkedLists[i];

all.addAll(deque);

}

return all;

}

public void clear() {

initDeques();

}

public int size() {

return size;

}

public boolean isEmpty() {

return size == 0;

}

public ListIterator iterator() {

return new PriorityLinkedListIterator(linkedLists);

}

protected void initDeques() {

linkedLists = new LinkedList[priorities];

for (int i = 0; i < priorities; i++) {

linkedLists[i] = new LinkedList();

}

size = 0;

}

class PriorityLinkedListIterator implements ListIterator {

private LinkedList[] lists;

private int index;

private ListIterator currentIter;

PriorityLinkedListIterator(LinkedList[] lists) {

this.lists = lists;

index = lists.length - 1;

currentIter = lists[index].listIterator();

}

public void add(Object arg0) {
throw new UnsupportedOperationException();
}

public boolean hasNext() {
if (currentIter.hasNext()) {
return true;
}
while (index >= 0) {
if (index == 0 || currentIter.hasNext()) {
break;
}
index--;
currentIter = lists[index].listIterator();
}
return currentIter.hasNext();
}

public boolean hasPrevious() {
throw new UnsupportedOperationException();
}

public Object next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return currentIter.next();
}

public int nextIndex() {
throw new UnsupportedOperationException();
}

public Object previous() {
throw new UnsupportedOperationException();
}

public int previousIndex() {
throw new UnsupportedOperationException();
}

public void remove() {
currentIter.remove();
size--;
}

public void set(Object obj) {
throw new UnsupportedOperationException();
}

}

}

26、生成list的帮助类（来自google）

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import java.util.ArrayList;

import java.util.Collections;

import java.util.LinkedList;

import java.util.List;

public class Lists {

private Lists() { }

public static ArrayList newArrayList() {

return new ArrayList();

}

public static ArrayList newArrayListWithCapacity(int initialCapacity) {

return new ArrayList(initialCapacity);

}

public static ArrayList newArrayList(E… elements) {

ArrayList set = newArrayList();

Collections.addAll(set, elements);

return set;

}

public static ArrayList newArrayList(Iterable