Chessboard.java

import java.util.Arrays;
import java.util.Random;

/**
 * Created by IntelliJ IDEA.
 * User: ASUS
 * Date: 12.02.12
 * Time: 15:11
 * To change this template use File | Settings | File Templates.
 */
interface Pieces { void move(); }

class King implements Pieces {
    public void move() { System.out.println("King.move()"); }
    public String toString() { return "King"; }
}
class Queen implements Pieces {
    public void move() { System.out.println("Queen.move()"); }
    public String toString() { return "Queen"; }
}
class Knight implements Pieces {
    public void move() { System.out.println("Knight()"); }
    public String toString() { return "Knight"; }
}

class Gen {
    private static Random random = new Random();
    static Pieces choice() {
        switch(random.nextInt(3)) {
            case 0 : return new King();
            case 1 : return new Queen();
            case 2 : return new Knight();
        
            default : return null;
        }
    }
}

public class Chessboard{
    static void moveAll(Pieces[] pieces) {
        for(Pieces p : pieces)
            p.move();
    }

    
    public static void main(String[] args) {
        Pieces[] pieces = new Pieces[20];

        for(int i = 0; i < pieces.length; i++)
            pieces[i] = Gen.choice();

        System.out.println("All pieces on a chessboard: " + Arrays.toString(pieces));
        moveAll(pieces);
    }
}