All,

I'm going through the Friedman & Felleisen book "A Little Java, A Few Patterns". I'm trying to type the examples in DrJava, but I'm getting some errors. I'm a beginner, so I might be making rookie mistakes.

Here is what I have set-up:

public class ALittleJava {
  //ABSTRACT CLASS POINT
  abstract class Point {
    abstract int distanceToO();
  }
  class CartesianPt extends Point {
    int x;
    int y;
    int distanceToO(){
      return((int)Math.sqrt(x*x+y*y));
    }
    CartesianPt(int _x, int _y) {
    x=_x;
    y=_y;
    }
  }
  class ManhattanPt extends Point {
    int x;
    int y;
    int distanceToO(){
      return(x+y);
    }
    ManhattanPt(int _x, int _y){
      x=_x;
      y=_y;
    }
  }
}

And on the main's side:

public class Main{
  public static void main (String [] args){
    Point y = new ManhattanPt(2,8);
    System.out.println(y.distanceToO());
  }
}

The compiler cannot find the symbols Point and ManhattanPt in the program.

If I precede each by ALittleJava., I get another error in the main, i.e.,

an enclosing instance that contains ALittleJava.ManhattanPt is required

I've tried to find ressources on the 'net, but the book must have a pretty confidential following and I couldn't find much.

Thank you all.

JDelage