HELP NEEDED FOR CALLING METHOD OF THE SAME CLASS

[Yasser Shaikh]

class GameShape {
public void displayShape() {
System.out.println("displaying shape");
}
// more code
}
88 Chapter 2: Object Orientation
class PlayerPiece extends GameShape {
public void movePiece() {
System.out.println("moving game piece");
}
// more code
}
class TilePiece extends GameShape {
public void getAdjacent() {
System.out.println("getting adjacent tiles");
}
// more code
}
Now imagine a test class has a method with a declared argument type of
GameShape, that means it can take any kind of GameShape. In other words,
any subclass of GameShape can be passed to a method with an argument of type
GameShape. This code
public class TestShapes {
public static void main (String[] args) {
PlayerPiece player = new PlayerPiece();
TilePiece tile = new TilePiece();
doShapes(player);
doShapes(tile);
}
public static void doShapes(GameShape shape) {
shape.displayShape();
}
}

Outputs:
displaying shape
displaying shape

this is what i found in my scjp book while studying ...
but when i was trying to run this piece of code on my pc i got an error...
which i then corrected by just creating an object of the TestShape class
and calling doShapes method with that object...
please guide me!

[Jason Irwin]

What is it you do not understand?

The code from K&B works as it is written in the book (SCJP6, Chapter 2, Inheritance, Is-A, Has-A, page 91), I get no exceptions, just he output as described. What exception did you get?

I can't see why you need an instance of TestShape - it's static methods you are calling and they do not require an object instance, they can be called on the class instance.

[Yasser Shaikh]

No... i dont get exceptions i got two errors they are listed below:

C:\Documents and Settings\RNS\My Documents\TestShape.java:35: non-static method doShape(GameShape) cannot be referenced from a static context
doShape(player);
^
C:\Documents and Settings\RNS\My Documents\TestShape.java:36: non-static method doShape(GameShape) cannot be referenced from a static context
doShape(tile);
^
2 errors

and didnt get what you are trying to say...
its not the static method that i am callin ....
doShapes() is a non-static method...
please reply ASAP!!

[Maneesh Godbole]

Please keep it down. Also Ease up

[Jason Irwin]

Yasser - the code you presented here works perfectly and "doShapes" is static, but in your program you get an error. What does that tell you?

Your program has at least two mistakes in it.

1) There should be no "doShape" method, but should be a "doShapes" method.
2) Carefully check your declaration of the "doShapes" method. I think you'll find something missing. Clue: it begins with "s".

[David Newton]

I don't even see any code that could generate that error.

[Jason Irwin]

In the code they have posted, no.

In the code they typed into their source file? Different question.