我有看起来像这样的代码：
public class A
{
public void doStuff()
{
System.out.print("Stuff successfully done");
}
}
public class B extends A
{
public void doStuff()
{
System.out.print("Stuff successfully done, but in a different way");
}
public void doMoreStuff()
{
System.out.print("More advanced stuff successully done");
}
}
public class AWrapper
{
public A member;
public AWrapper(A member)
{
this.member = member;
}
public void doStuffWithMember()
{
a.doStuff();
}
}
public class BWrapper extends AWrapper
{
public B member;
public BWrapper(B member)
{
super(member); //Pointer to member stored in two places:
this.member = member; //Not great if one changes, but the other does not
}
public void doStuffWithMember()
{
member.doMoreStuff();
}
}
但是,此代码存在问题.我在两个地方存储了对该成员的引用,但是如果其中一个改变而另一个没有改变,可能会有麻烦.我知道在Java中,继承的方法可以将其返回类型(可能还有参数,但我不确定)的范围缩小到派生类.领域也是如此吗？
