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
[java]
view plaincopyimport java.util.LinkedList;
public class LinkedListTest{
public static void main(String[] args) {
LinkedList<String> lList = new LinkedList<String>();
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 [java]
view plaincopyfor (String str: lList) {
System.out.println(str);
}
3、从链表生成子表
[java]
view plaincopyList 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.
[java]
view plaincopyimport 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
[java]
view plaincopypublic 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
[java]
view plaincopyimport 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
[java]
view plaincopyimport 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
[java]
view plaincopyArrayList<String> arrayList = new ArrayList<String>(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
[java]
view plaincopyimport java.util.LinkedList;
public class Main {
public static void main(String[] args) {
LinkedList<String> lList = new LinkedList<String>();
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
[java]
view plaincopyimport java.util.LinkedList;
public class Main {
public static void main(String[] args) {
LinkedList<String> lList = new LinkedList<String>();
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
[java]
view plaincopyimport java.util.LinkedList;
public class Main {
public static void main(String[] args) {
LinkedList<String> lList = new LinkedList<String>();
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
[java]
view plaincopyimport java.util.LinkedList;
import java.util.List;
public class Main {
public static void main(String[] args) {
List<String> theList = new LinkedList<String>();
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
[java]
view plaincopyimport java.util.LinkedList;
import java.util.List;
public class Main {
public static void main(String[] args) {
List<String> theList = new LinkedList<String>();
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
[java]
view plaincopyimport java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
public class Main {
public static void main(String[] args) {
LinkedList<String> myQueue = new LinkedList<String>();
myQueue.add("A");
myQueue.add("B");
myQueue.add("C");
myQueue.add("D");
List<String> myList = new ArrayList<String>(myQueue);
for (Object theFruit : myList)
System.out.println(theFruit);
}
}
16、实现栈
[java]
view plaincopyimport 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
[java]
view plaincopyimport 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
[java]
view plaincopyimport 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
[java]
view plaincopyimport java.util.LinkedList;
public class Main {
public static void main(String[] args) {
LinkedList<String> lList = new LinkedList<String>();
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
[java]
view plaincopyimport java.util.LinkedList;
public class Main {
public static void main(String[] args) {
LinkedList<String> lList = new LinkedList<String>();
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
[java]
view plaincopyimport 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<Address> ml = new LinkedList<Address>();
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
[java]
view plaincopyimport java.util.LinkedList;
public class Main {
public static void main(String[] args) {
LinkedList<String> lList = new LinkedList<String>();
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
[java]
view plaincopyObject[] objArray = lList.toArray();
for (Object obj: objArray) {
System.out.println(obj);
}
24、链表多线程
[java]
view plaincopyimport java.util.Collections;
import java.util.LinkedList;
import java.util.List;
class PrepareProduction implements Runnable {
private final List<String> queue;
PrepareProduction(List<String> q) {
queue = q;
}
public void run() {
queue.add("1");
queue.add("done");
}
}
class DoProduction implements Runnable {
private final List<String> queue;
DoProduction(List<String> 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<String>());
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）
[java]
view plaincopyimport 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）
[java]
view plaincopyimport java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
public class Lists {
private Lists() { }
public static <E> ArrayList<E> newArrayList() {
return new ArrayList<E>();
}
public static <E> ArrayList<E> newArrayListWithCapacity(int initialCapacity) {
return new ArrayList<E>(initialCapacity);
}
public static <E> ArrayList<E> newArrayList(E... elements) {
ArrayList<E> set = newArrayList();
Collections.addAll(set, elements);
return set;
}
public static <E> ArrayList<E> newArrayList(Iterable<? extends E> elements) {
ArrayList<E> list = newArrayList();
for(E e : elements) {
list.add(e);
}
return list;
}
public static <E> LinkedList<E> newLinkedList() {
return new LinkedList<E>();
}
}
