java - 抽象类错误简单类

Question

public abstract class Shape{
    
    protected Point position;
    
    public Shape (Point p)
    {
        this.position=new Point(p);
    }
    
    public abstract int getArea();
    public abstract int gerPerimeter();
    public abstract boolean overlap(Shape other);
    
}

public class Rectangle extends Shape
{
    public int width;
    public int height;
    
    public Rectangle(Point position,int width,int height)
    {
        super(position);
        this.width=width;
        this.height=height;
    }
    @Override
    public int getArea()
    {
        return width*height;
    }
    @Override
    public int getPerimeter()
    {
        return width*2+height*2;
    }
    @Override
    public boolean overlap(Rectangle other)
    {
        return false;
    }
}
    

<小时/>

Rectangle.java:1: error: Rectangle is not abstract and does not override abstract method overlap(Shape) in Shape

public class Rectangle extends Shape
^

Rectangle.java:17: error: method does not override or implement a method from a supertype

@Override
^

Rectangle.java:22: error: method does not override or implement a method from a supertype

@Override
^

3 errors

Answer 1

这个方法public boolean Overlap(Rectangle other)和这个

publicabstractbooleanoverlap(Shapeother);不一样，

即使矩形扩展/实现形状是真的...

所以从技术上讲，你并没有重写抽象类的所有方法......

和 Override 注释给你一个提示，因为该方法可以在父类(super class)中找到......