ArrayList<Ls> ff=new ArrayList()<Ls>;

Ls ls1=new Ls("薯片",5f);

ff.add(ls1);

Ls cls=ff.get(0);//这里不再需要强转

 

 

import java.util.*;

public class L4_6

{

  public static void main(String[] args)

  {

          //Hashtable ff=new Hashtable();       

       ArrayList ff=new ArrayList();

       Ls ls1=new Ls("薯片",5f);

       ff.add(ls1);

     Ls cls=(Ls)ff.get(0);

       Yl hyl=(Yl)ff.get(0);//这样显然是不对的

     }

}

class Ls

{

  private String mingcheng;

  private float jiage;

 

  Ls(String mingcheng,float jiage)

  {

      this.mingcheng=mingcheng;

      this.jiage=jiage;

  }

}

class Yl

{

  private String mingcheng;

  private float jiage;

  private String yanse;

 

  Yl(String mingcheng,float jiage,String yanse)

  {

      this.mingcheng=mingcheng;

      this.jiage=jiage;

      this.yanse=yanse;

  }

}