子类:public class ShapeCircle extends Shape
{
protected double r;
public ShapeCircle()
{
setside(0.0);
}
public ShapeCircle(double r)
{
setside(r);
}

public void setside(double r)
{
this.r=r;
}
public double perimeter()
{
return Math.PI*2*r;
}
public String getType()
{
return "Circle";
}
}
父类:
import ShapeCircle;
import Shape;
public class Myshape
{

private static ShapeCircle sc=new ShapeCircle(4);
private static Shape shapej=new ShapeCircle(5);
public static void main(String args[])
{
System.out.println(sc.getType()+","+sc.perimeter());
}
shapej=sc;
System.out.println(shape.getType()+","+shape.perimeter());


}
当编译到shapej=sc总报错.为什么,请高手指教.

public static void main(String args[])
{
System.out.println(sc.getType()+","+sc.perimeter());
shapej=sc;
System.out.println(shapej.getType()+","+shapej.perimeter());
}

你的语句不能直接写在类里，如果写的话可写为
static {
shapej=sc;
System.out.println(shape.getType()+","+shape.perimeter());
}

或者写成：　karma(无为)的方式

I guess dongjh forgot to put } after 
System.out.println(shape.getType()+","+shape.perimeter());