arraylist的增删改查

import java.util.ArrayList; import java.util.Iterator; /*arraylist 存储数据是有序的 可重复的， 适合查询 遍历 * * **/ public class arrayListDemo { public static void main(String[] args) { ArrayList list=new ArrayList(); //添加元素 list.add("张三"); list.add("李四"); list.add("王五"); // 遍历元素 for (Object name : list) { System.out.println(name); } System.out.println("*********************"); //修改元素 list.set(0, "刘三"); Iterator it=list.iterator(); while (it.hasNext()) { System.out.println(it.next()); } System.out.println("********************"); //删除元素 boolean in= list.remove("刘三"); System.out.println(in); for (int i = 0; i < list.size(); i++) { System.out.println(list.get(i)); } //查询王五的下标 int a= list.indexOf("王五"); System.out.println(a); //清空list int b=list.indexOf("张三"); System.out.println(b); boolean bool=list.contains("李四"); System.out.println("查询是否有李四这个人："+bool); boolean bool1=list.isEmpty(); System.out.println("判断list集合是否为空"+bool1); System.out.println(list.indexOf(0)); list.clear(); } }