package test; import java.util.*; import javax.security.auth.kerberos.KerberosKey; import java.io.*; import java.math.BigInteger; public class Main { private static final String space_operator = " "; public static void main(String[] args) throws Exception { Scanner scanner = new Scanner(new BufferedInputStream(System.in)); PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out)); List list = new ArrayList(); //添加 list.add("avd1"); list.add("avd2"); list.add("avd3"); list.add("avd4"); list.add("avd5"); //在指定位置添加 list.add(1,"avd9"); System.out.println(list); //删除 list.remove(1); System.out.println(list); //查看 System.out.println(list.get(1)); //设置 list.set(1, "ssd"); System.out.println(list); //获取子序列 System.out.println(list.subList(1, 2)); //取出元素的方法 //迭代器方法 此迭代器方法不能进行集合操作 Iterator it = list.iterator(); while(it.hasNext()) { Object obj = it.next(); if(obj == "avd3") { //list.add("dssd"); // 会出现错误java.util.ConcurrentModificationException //在迭代器中不能用集合操作 反之亦然,因为这样容易出现并发错误 } else { System.out.println(obj); } } for(int i = 0; i < list.size(); i ++) { System.out.println(list.get(i)); } //迭代器取出元素list专有方法可以直接在迭代器进行改变元素 //从第一个元素开始 ListIterator it1 = list.listIterator(); //从任意元素开始 ListIterator it2 = list.listIterator(1); //向后遍历迭代器 while(it1.hasNext()) { Object obj = it1.next(); if(obj.equals("avd3")) { it1.add("avd7"); } else { System.out.println(obj); } } System.out.println(list); System.out.println(it1.hasNext()); System.out.println(it1.hasPrevious()); //向前遍历迭代器 while(it1.hasPrevious()) { System.out.println(it1.previous()); } } }