Java题目怎么解啊

Java题目怎么解啊

接口IContainer

实现类

追问大佬大佬可以给个完整的嘛 跪求

//ArrayList.java
package test;

import java.util.List;

public class ArrayList implements IContainer{
private List list;
@Override
public void add(Integer a) {
//为空要new一下
if(this.getList()==null){
//该出的ArrayList非你自己定义的类
this.list=new java.util.ArrayList();
}
this.list.add(a);

}

@Override
public int size() {
// TODO Auto-generated method stub
return list.size();
}

public List getList() {
return list;
}

public void setList(List list) {
this.list = list;
}
public static void main(String[] args) {
IContainer ic=new ArrayList();
ic.add(1);
ic.add(2);
//打印长度
System.out.println(ic.size());
}
}
//IContainer.java
package test;

public interface IContainer {
public void add(Integer a);
public int size();
}