简单实现一个LinkedList的增删改查

简单实现一个LinkedList的增删改查

LinkedList简介
LinkedList 是一个继承于AbstractSequentialList的双向链表。它也可以被当作堆栈、队列或双端队列进行操作。
LinkedList 实现 List 接口，能对它进行队列操作。
LinkedList 实现 Deque 接口，即能将LinkedList当作双端队列使用。
LinkedList 实现了Cloneable接口，即覆盖了函数clone()，能克隆。
LinkedList 实现java.io.Serializable接口，这意味着LinkedList支持序列化，能通过序列化去传输。
LinkedList 是非同步的。
LinkedList底层用双向链表实现的存储，特点是查询效率低，增删效率高，线程不安全。

LinkedList代码实现：
Node.java
package LLT;

public class Node {
Node pre;
Node next;
Object obj;

public Node(Node pre, Node next, Object obj) {
super();
this.pre = pre;
this.next = next;
this.obj = obj;
}

public Node(Object obj) {
super();
this.obj = obj;
}

}

TLinkedList.java
package LLT;

public class TLinkedList {
private Node first;
private Node last;
private int size;

public void add(Object obj) {
Node node = new Node(obj);
if (first == null) {
node.pre = null;
node.next = null;
first = node;
last = node;
} else {
node.pre = last;
node.next = null;
last.next = node;
last = node;
}
size++;
}

public Object get(int index) {
if (index < 0 || index > size - 1) {
throw new RuntimeException("索引数字不合法" + index);
}
Node temp = null;
if (index <= (size >> 1)) {
temp = first;
for (int i = 0; i < index; i++) {
temp = temp.next;
}
} else {
temp = last;
for (int i = size - 1; i > index; i--) {
temp = temp.pre;
}
}
return temp.obj;
}

public Node getNode(int index) {
Node temp = null;
if (index <= (size >> 1)) {
temp = first;
for (int i = 0; i < index; i++) {
temp = temp.next;
}
} else {
temp = last;
for (int i = size - 1; i > index; i--) {
temp = temp.pre;
}
}
return temp;
}

public void remove(int index) {
Node temp = getNode(index);
if (temp != null) {
Node up = temp.pre;
Node down = temp.next;
if (up != null) {
up.next = down;
}
if (down != null) {
down.pre = up;
}
if (index == 0) {
first = down;
}
if (index == size - 1) {
last = up;
}
size--;
}
}

public int size() {
return size;
}

public void add(int index, Object obj) {
Node node = new Node(obj);
Node temp = getNode(index);
if (temp != null) {
Node up = temp.pre;
up.next = node;
node.pre = up;
temp.pre = node;
node.next = temp;
size++;
}
}

public void set(int index, Object obj) {
Node temp = getNode(index);
temp.obj = obj;
}

}