java – 抽象类的目的/用途是什么？ (寻找现实世界的例子.)

发布时间：2020-12-15 05:16:35 所属栏目：Java 来源：网络整理

导读：有人可以给我看一下 Java中抽象类的例子吗？具有真实世界应用程序(而不是教科书样本)的东西将是更可取的. 谢谢！解决方法阅读本教程 Abstract Methods and Classes. First,you declare an abstract class , GraphicObject,to provide member variables and

有人可以给我看一下 Java中抽象类的例子吗？具有真实世界应用程序(而不是教科书样本)的东西将是更可取的.

谢谢！

解决方法

阅读本教程 Abstract Methods and Classes.

First,you declare an abstract class,
GraphicObject,to provide member
variables and methods that are wholly
shared by all subclasses,such as the
current position and the moveTo
method. GraphicObject also declares
abstract methods for methods,such as
draw or resize,that need to be
implemented by all subclasses but must
be implemented in different ways. The
GraphicObject class can look something
like this:

abstract class GraphicObject {
    int x,y;
    ...
    void moveTo(int newX,int newY) {
        ...
    }
    abstract void draw();
    abstract void resize();
}

Each non-abstract subclass of
GraphicObject,such as Circle and
Rectangle,must provide
implementations for the draw and
resize methods:

class Circle extends GraphicObject {
    void draw() {
        ...
    }
    void resize() {
        ...
    }
}
class Rectangle extends GraphicObject {
    void draw() {
        ...
    }
    void resize() {
        ...
    }
}

（编辑：李大同）

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