Question

I am trying to run the following simple code,

public abstract class Shape{
    abstract double area();
    abstract double circumference();

    public void show()
    {
        System.out.println("Area = "+area());
        System.out.println("Circumference = "+circumference());
    }
}

public class Circle extends Shape{
    double r;

    public double area()
    {
        return 3.14*r*r;
    }

    double circumference()
    {
        return 2*3.14*r;
    }


    Circle(double radius)
    {
        r=radius;
    }
}


public class Rectangle extends Shape{
    double x,y;

    double area()
    {
        return x*y;
    }

    double circumference()
    {
        return 2*(x+y);
    }

    Rectangle(double length, double width)
    {
        x = length;
        y = width;
    }
}

public class Geometry
{
    Circle r = new Circle(2.22);
    Rectangle s = new Rectangle(2.33, 3.44);
    r.show();
}

But I keep getting identifier expected error from Java compiler. What am I doing wrong. Everything is public and there seems to be no syntax error. Please help.

Answer 1

This is the problem:

class Geometry
{
    Circle r = new Circle(2.22);
    Rectangle s = new Rectangle(2.33, 3.44);
    r.show();
}

Your final statement doesn’t declare a variable – it’s just a statement. That needs to belong in an initializer block, constructor or method. For example:

public class Geometry {
    public static void showCircle() {
        Circle r = new Circle(2.22);
        Rectangle s = new Rectangle(2.33, 3.44);
        r.show();
    }
}

Note that this has nothing to do with inheritance – this code will give the same problem:

class Test {
    System.out.println("Oops");
}