继承问题
我目前所明白的继承是子类对父类属性的拓展
例如：一个父类person()里有年龄，姓名两个属性
子类student（）里在person（）的基础上加上一个学号的属性
但是最近看到这样的代码，让我对继承又有重新的看法
- Java code
package ex11_01;/**This is a generic container class to store a list of objects * * @author WangDong *@version 19th December 2011 */public class ObjectList { private Object[] list; //之前并未写过Object类，后面别的类继承竟然可以直接用 private int total; /**Constructor intitialises an empty list * @param sizeIn Used to set the maximum size of the list */ public ObjectList(int sizeIn){ list=new Object[sizeIn]; total=0; } /**Add an object to the end of the list * @param objectIn The object to add * @return Returns true if the object was added successfuly * add false otherwise */ public boolean add(Object objectIn){ if(!isFull()){ list[total]=objectIn; total++; return true; } else{ return false; } } /**Reports on whether or not the list is empty * @return Returns true if the list is empty * and false otherwise */ public boolean isEmpty(){ if(total==0){ return true; } else{ return false; } } /**Reports on whether or not the list is full * @return Returns true if the list is full * and false otherwise */ public boolean isFull(){ if(total==list.length){ return true; } else{ return false; } } /**Reads an object from a specified position in the list * @param i The position of the object in the list * @return Returns the object at the specified position in the list * or null if no object is at at that position */ public Object getItem(int positionIn){ if(positionIn<1||positionIn>total){ return null; } else{ return list[positionIn-1]; } } /**Reads the number of objects stored in the list*/ public int getTotal(){ return total; } /**Remove an object from the specified position in the list * @param numberIn The position of the object to be removed * @return Returns true of the item is removed successfully * and false otherwise */ public boolean remove(int numberIn){ if(numberIn>=1&&numberIn<=total){ for(int i=numberIn-1;i<=total-2;i++){ list[i]=list[i+1]; } total--; return true; } else{ return false; } } }下面是他的一个子类
- Java code
package ex11_01;/**Collection class to hold a list of Payment objects * * @author WangDong *@version 19th December 2011 */public class PaymentList extends ObjectList{ /**Constructor initialises the empty list and sets the maximum list size */ public PaymentList(int sizeIn){ super(sizeIn); //Call ObjectList constructor } /**Reads the payment at the given position in the list * @param positionIn The position of the payment in the list * @return Returns the payment at the position */ public Payment getPayment(int positionIn){ if(positionIn<1||positionIn>getTotal()){ //No object found at given position return null; } else{ //Call inherited method and type cast return (Payment)super.getItem(positionIn); //这里直接强制转换一下就可以吗 } } /**Returns the total value of payments recorded*/ public double calculateTotalPaid(){ double totalPaid=0;//Intialize total paid //Loop throuth all payments for(int i=1;i<=super.getTotal();i++){ totalPaid+=getPayment(i).getAmount(); } return totalPaid; }}之前没有写过Object类，写过Payment类，可以直接进行强制转换吗
刚刚学Java，继承到底是什么样的呢
[解决办法]
Object 所以累得父类。。。当然可以直接用
[解决办法]
不太清楚你想问什么
你给的代码是别人实现的一个list数据结构，没什么特别。
java有自己的容器，不太需要像代码这样自己去实现。
另外继承的话，就是父类对所有子类公有属性的一个抽象。
[解决办法]