java类 - Java / Java SE

要求圆柱继承圆，圆继承点。写出来很多错，请人指点

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Java code:

class Point
{
int x, y;
public Point()
{
x = 0;
y = 0;
}
public Point(int newx, int newy)
{
x = newx >= 0 ? newx : 0;
y = newy >= 0 ? newy : 0;

}
public int get_x()
{
return x;
}
public int get_y()
{
return y;
}
public void set_x(int temp)
{
x = temp;
}
public void set_y(int temp)
{
y = temp;
}

}
class Circle extends Point
{

double r;
public Circle()
{
r = 0.0;
}
public Circle(int x, int y, double r)
{
super(x,y);
this.r = r;
}
public double get_r()
{
return r;
}
public void set_r(double newr)
{
this.r = newr;
}
public double cir_c()
{
return 2 * 3.1415926 * r;
}

public double cir_s()
{
return 3.1415926 * r * r;
}
}

class Column extends Circle
{
double h;
public Column()
{
h = 0;
}
public Column(int x, int y, double r, double h)
{
super(x, y, r);
this.h = h;
}
public double get_h()
{
return h;
}
public void set_h(double newh)
{
this.h = newh;
}
public double col_s()
{
return (2 * 3.1415926 * r * r + h * 2 * 3.1415926 * r);
}

public double col_v()
{
return (3.1415926 * r * r * h);
}
}

public class Test {
public static void main(String args[])
{
Column c = new Column(3,3,2.0,5.5);
System.out.println("X = "+c.get_x());
System.out.println("Y = "