Java跳躍表是一種基于有序鏈表的數(shù)據(jù)結(jié)構(gòu)，它通過快速跳躍的方式實現(xiàn)了類似于二叉樹的查找和插入操作，具有高效、簡單、實用等優(yōu)點。

跳躍表的結(jié)構(gòu)由多級鏈表組成，每一級鏈表都是有序的，并且每一級鏈表的節(jié)點數(shù)隨著級別的增加而逐漸減少，從而滿足在不增加時間復(fù)雜度的前提下提高平均查詢和插入效率的要求。

public class SkipList {
private static final double P = 0.5;
private SkipListNode head;
private int levels;
private Random random;
public SkipList() {
head = new SkipListNode(Integer.MIN_VALUE);
random = new Random();
}
public boolean contains(int value) {
SkipListNode node = findNode(value);
return node != null && node.value == value;
}
public void insert(int value) {
SkipListNode node = new SkipListNode(value);
insertNode(node);
}
private void insertNode(SkipListNode node) {
int level = 0;
while (random.nextDouble()< P) {
level++;
}
while (levels< level) {
SkipListNode newHead = new SkipListNode(Integer.MIN_VALUE);
newHead.down = head;
head = newHead;
levels++;
}
SkipListNode cur = head;
SkipListNode pre = null;
while (cur != null) {
if (cur.value == node.value) {
cur.value = node.value;
return;
}
if (cur.value >node.value) {
if (pre != null) {
node.down = pre.next;
pre.next = node;
}
break;
}
pre = cur;
cur = cur.next;
if (cur == null) {
if (pre != null) {
node.down = pre.next;
pre.next = node;
cur = node.down;
} else {
cur = node;
}
break;
}
}
while (random.nextDouble()< P && levels< level) {
SkipListNode newHead = new SkipListNode(Integer.MIN_VALUE);
newHead.down = head;
head = newHead;
levels++;
SkipListNode upNode = new SkipListNode(node.value);
upNode.down = node;
SkipListNode preNode = head;
SkipListNode curNode = preNode.next;
while (curNode != null && curNode != cur) {
preNode = curNode;
curNode = curNode.next;
}
preNode.next = upNode;
upNode.next = curNode;
node = upNode;
}
}
private SkipListNode findNode(int value) {
SkipListNode cur = head;
while (cur != null) {
if (cur.value == value) {
return cur;
}
if (cur.value >value) {
cur = cur.down;
if (cur == null) {
return null;
}
} else {
cur = cur.next;
}
}
return null;
}
private class SkipListNode {
int value;
SkipListNode next = null;
SkipListNode down = null;
public SkipListNode(int value) {
this.value = value;
}
}
}

上面的代碼實現(xiàn)了跳躍表的基本功能，包括查找節(jié)點、插入節(jié)點等操作。其中使用了隨機(jī)數(shù)來確定每個節(jié)點的級別，并根據(jù)級別插入節(jié)點到相應(yīng)的鏈表中。關(guān)于跳躍表的更多應(yīng)用以及其他實現(xiàn)方式，讀者可以自行查閱相關(guān)資料。