public class Node {
protected Node next; //指針域 
public int data;//數據域 

public Node( int data) { 
this. data = data; 
} 
//顯示此節(jié)點 
public void display() { 
System. out.print( data + " "); 
} 
}

public class LinkList {
public Node first; // 定義一個頭結點
private int pos = 0;// 節(jié)點的位置
public LinkList() {
this.first = null;
}
// 插入一個頭節(jié)點
public void addFirstNode(int data) {
Node node = new Node(data);
node.next = first;
first = node;
}
// 刪除一個頭結點,并返回頭結點
public Node deleteFirstNode() {
Node tempNode = first;
first = tempNode.next;
return tempNode;
}
// 在任意位置插入節(jié)點 在index的后面插入
public void add(int index, int data) {
Node node = new Node(data);
Node current = first;
Node previous = first;
while (pos != index) {
previous = current;
current = current.next;
pos++;
}
node.next = current;
previous.next = node;
pos = 0;
}
// 刪除任意位置的節(jié)點
public Node deleteByPos(int index) {
Node current = first;
Node previous = first;
while (pos != index) {
pos++;
previous = current;
current = current.next;
}
if (current == first) {
first = first.next;
} else {
pos = 0;
previous.next = current.next;
}
return current;
}
// 根據節(jié)點的data刪除節(jié)點(僅僅刪除第一個)
public Node deleteByData(int data) {
Node current = first;
Node previous = first; // 記住上一個節(jié)點
while (current.data != data) {
if (current.next == null) {
return null;
}
previous = current;
current = current.next;
}
if (current == first) {
first = first.next;
} else {
previous.next = current.next;
}
return current;
}
// 顯示出所有的節(jié)點信息
public void displayAllNodes() {
Node current = first;
while (current != null) {
current.display();
current = current.next;
}
System.out.println();
}
// 根據位置查找節(jié)點信息
public Node findByPos(int index) {
Node current = first;
if (pos != index) {
current = current.next;
pos++;
}
return current;
}
// 根據數據查找節(jié)點信息
public Node findByData(int data) {
Node current = first;
while (current.data != data) {
if (current.next == null)
return null;
current = current.next;
}
return current;
}
}

public class TestLinkList {
public static void main(String[] args) { 
LinkList linkList = new LinkList(); 
linkList.addFirstNode(20); 
linkList.addFirstNode(21); 
linkList.addFirstNode(19); 
//print19,21,20 
linkList.add(1, 22); //print19,22,21,20 
linkList.add(2, 23); //print19,22,23,21,20 
linkList.add(3, 99); //print19,22,23,99,21,20 
//調用此方法會print 19,22,23,99,21,20 
linkList.displayAllNodes(); 
}
}