List是个接口,ArrayList是List接口的实现类
Collection
├List 接口
│├LinkedList 链表
│├ArrayList 顺序结构动态数组类
│└Vector 向量
│ └Stack 栈
└Set
Map
├Hashtable
├HashMap
└WeakHashMap List接口
package com.list;
import java.util.ArrayList;
import java.util.Iterator;
import com.login.User;
public class Arraylist {
public static void main(String[] args)
{
//创建字符型ArrayList
ArrayList<String> list = new ArrayList<String>();
list.add("aa");
list.add("bb");
list.add("cc");
for(int i = 0;i<list.size();i++){
System.out.println(list.get(i));
}
//迭代器用于for循环遍历字符类型的list
for (Iterator<String> iter = list.iterator(); iter.hasNext();) {
String str = (String)iter.next();
System.out.println(str);
}
//迭代器一般用while循环遍历字符类型的list
Iterator<String> iter = list.iterator();
while(iter.hasNext()){
String str = (String) iter.next();
System.out.println(str);
}
//创建对象型ArrayList
ArrayList<User> userArrayList = new ArrayList<User>();
for(int i=0;i<3;i++){
User user = new User();
user.setUsername("a"+i);
user.setPassword("b"+i);
userArrayList.add(user);
}
for(int i = 0;i<userArrayList.size();i++){
System.out.println(userArrayList.get(i).getUsername()+userArrayList.get(i).getPassword());
}
//迭代器用于for循环遍历对象类型的list
for (Iterator<User> iter1 = userArrayList.iterator(); iter1.hasNext();) {
User user = iter1.next();
System.out.println(user.getUsername()+","+user.getPassword());
}
//迭代器一般用while循环遍历对象类型的list
Iterator<User> iter1 = userArrayList.iterator();
while(iter1.hasNext()){
User user = iter1.next();
System.out.println(user.getUsername()+","+user.getPassword());
}
}
}