【java API基本实现】ArrayList

ArrayList:

 package com.tn.arraylist;

 public class ArrayList {

     Object[] objects=new Object[10];
     int index=0;

     public void add(Object o){
         if(index==objects.length){
             Object[] newobjects=new Object[objects.length*2];
             System.arraycopy(objects, 0, newobjects, 0, index);
             objects=newobjects;
         }
         objects[index++]=o;
     }

     public int size(){
         return index;
     }

 }

客户端测试类Test：

 package com.tn.arraylist;

 public class Test {
     public static void main(String[] args) {
         ArrayList al=new ArrayList();
         for(int i=0;i<34;i++){
             al.add(new Object());
         }
         System.out.println(al.size());
     }
 }