java 单链表实现

package com.jack.link;

public class LinkItem {
//数据域
private Object obj;
private LinkItem next;

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

public Object getObj() {
return obj;
}

public void setObj(Object obj) {
this.obj = obj;
}

public LinkItem getNext() {
return next;
}

public void setNext(LinkItem next) {
this.next = next;
}

}

package com.jack.link;

import static java.lang.System.out;

public class LinkList {
private LinkItem first;

public void display() {
if(!isEmpty()) {
LinkItem item = first;
while(item != null) {
out.print(item.getObj() + "-->");
item = item.getNext();
}

out.println(" ");
} else {
out.println("linkList is empty");
}
}

public boolean isEmpty() {
return first == null;
}

//插入头结点   时间复杂度O(1)
public void insertFirst(LinkItem item) {
item.setNext(first);
first = item;
}

//删除头结点 时间复杂度O(1)
public void deleteFirst() {
if(!isEmpty()) {
first = first.getNext();
} else {
out.println("linkList is empty");
}
}

//查询指定结点   时间复杂度O(N)
public LinkItem find(Object key) {
LinkItem result = null;
if(!isEmpty()) {
LinkItem item = first;
while(item != null) {
if(item.getObj().equals(key)) {
result = item;
break;
} else {
item = item.getNext();
}
}
} else {
out.println("linkList is empty");
}
return result;
}

//删除指定结点  时间复杂度 
public void remove(Object key) {
if(!isEmpty()) {
if(first.getObj().equals(key)) {
first = first.getNext();
} else {
LinkItem previous = first;
LinkItem current = first.getNext();
while(current != null) {
if(current.getObj().equals(key)) {
previous.setNext(current.getNext());
} 
previous = current;
current = current.getNext();
}
}
} else {
out.println("linkList is empty");
}

}

public static void main(String[] args) {
LinkItem item5 = new LinkItem("50");
LinkItem item4 = new LinkItem("40");
LinkItem item3 = new LinkItem("30");
LinkItem item2 = new LinkItem("20");
LinkItem item1 = new LinkItem("10");

LinkList list = new LinkList();

list.display();
list.insertFirst(item1);
list.insertFirst(item2);
list.insertFirst(item3);
list.insertFirst(item4);
list.insertFirst(item5);
list.display();

list.deleteFirst();
list.display();

list.find("30");
list.remove("30");

list.display();

}

}