集合框架Aarray list

package edu.xcdq.list;

import java.util.ArrayList;
import java.util.List;

public class ArrayListDemo01 {
    public static void main(String[] args) {
        String[]str=new String[]{"1e21","12q","aqwdfqw"};
        str[0]="111";
        str[1]="222";
        str[2]="333";
        //删除位置为1的元素
        str[1]=str[2];
        str[2]=null;

        ArrayList list=new ArrayList<>();
        list.add("111");
        list.add("222");
        list.add("333");
        list.add("444");
        list.add("555");//增加
        System.out.println(list);
        list.remove(1);//删除
        list.remove("444");
        System.out.println(list);
        list.set(2,"55555");//修改
        System.out.println(list);
        //查询
        for (String l:list){
            System.out.println(l+"\t");
        }
        for (int i=0;i