/**
* 功能：实现单链表功能
*/
public class LinkList {
/* 用变量来实现表头 */
private Node Head = null;
/* 用变量来实现表尾 */
private Node Tail = null;
/* 用变量来实现当前位置 */
private Node Pointer = null; //
private int Length = 0;
public void deleteAll() {// 清空整个链表
Head = null;
Tail = null;
Pointer = null;
Length = 0;
}
// 链表复位，使第一个节点成为当前节点
public void reset() {
Pointer = null;
}
// 判断链表是否为空
public boolean isEmpty() {
return (Length == 0);
}
// 判断当前结点是否为最后一个结点
public boolean isEnd() {
if (Length == 0)
throw new java.lang.NullPointerException();
else if (Length == 1)
return true;
else
return (cursor() == Tail);
}
// 返回当前结点的下一个结点的值，并使其成为当前结点
public Object nextNode() {
if (Length == 1)
throw new java.util.NoSuchElementException();
else if (Length == 0)
throw new java.lang.NullPointerException();
else {
Node temp = cursor();
Pointer = temp;
if (temp != Tail)
return (temp.next.data);
else
throw new java.util.NoSuchElementException();
}
}
// 返回当前结点的值
public Object currentNode() {
Node temp = cursor();
return temp.data;
}
// 在当前结点前插入一个结点，并使其成为当前结点
public void insert(Object obj) {
Node e = new Node(obj);
if (Length == 0) {
Tail = e;
Head = e;
} else {
Node temp = cursor();
e.next = temp;
if (Pointer == null)
Head = e;
else
Pointer.next = e;
}
Length++;
}
//根据位置i，插入当前结点，若位置i不是当前节点
public boolean insert(Object obj,int i) {
boolean flag=false;
Node e = new Node(obj);
if (Length == 0) {
Tail = e;
Head = e;
Length++;
flag=true;
} else if(Length+1==i) {
Node temp = cursor();
e.next = temp;
if (Pointer == null)
Head = e;
else
Pointer.next = e;
Length++;
flag=true;
}else if (Length+1<i){
throw new Exception("z超出界，插入位置不能大于当前位置+1");
}else if (Length+1>i){
//从表头遍历，找到位置，将data的内容更新obj的值
int index=0;
Node cur=Head.next;
while(cur!=null){
if(index==i){
cur.data=obj;
flag=true;
break;
}
cur=cur.next;
index++;
}
flag=true;
}
}
// 返回链表的大小
public int size() {
return Length;
}
//根据位置i，删除当前节点
public boolean remove(Object obj,int i) {
Object temp;
boolean flag=false;
if (Length == 0)
throw new java.util.NoSuchElementException();
else if (Length == 1) {
temp = Head.data;
deleteAll();
flag=true;
} else {
//从表头遍历，找到删除的位置，删除
int index=0;
Node cur=Head.next;
while(cur!=null){
if(index+1==i){
cur.next=(Node)cur.next.next;
flag=true;
break;
}
cur=cur.next;
index++;
}
Length--;
}
return flag;
}
// 将当前结点移出链表，下一个结点成为当前结点，
// 如果移出的结点是最后一个结点，
// 则第一个结点成为当前结点
public Object remove() {
Object temp;
if (Length == 0)
throw new java.util.NoSuchElementException();
else if (Length == 1) {
temp = Head.data;
deleteAll();
} else {
Node cur = cursor();
temp = cur.data;
if (cur == Head)
Head = cur.next;
else if (cur == Tail) {
Pointer.next = null;
reset();
} else
Pointer.next = cur.next;
Length--;
}
return temp;
}
// 返回当前结点的指针
private Node cursor() {
if (Head == null)
throw new java.lang.NullPointerException();
else if (Pointer == null)
return Head;
else
return Pointer.next;
}
// 链表的简单应用举例
public static void main(String[] args) {
LinkList a = new LinkList();
for (int i = 1; i <= 10; i++)
a.insert(new Integer(i));
System.out.println("The currentNode is:" + a.currentNode());
while (!a.isEnd())
System.out.println("The nextNode is:" + a.nextNode());
a.reset();
while (!a.isEnd()) {
a.remove();
}
a.remove();
a.reset();
if (a.isEmpty()) {
System.out.println("There is no Node in List");
}
}
}
