享元模式Flyweight

//Purpose.  Flyweight design pattern
//
//Discussion.  Trying to use objects at very low levels of granularity is 
//nice, but the overhead may be prohibitive.  Flyweight suggests removing the
//non-shareable state from the class, and having the client supply it when
//methods are called.  This places more responsibility on the client, but,
//considerably fewer instances of the Flyweight class are now created.
//Sharing of these instances is facilitated by introducing a Factory class
//that maintains a "cache" of existing Flyweights.

class Gazillion {
private static int num = 0;
private int        row, col;
public Gazillion( int maxPerRow ) {
   row = num / maxPerRow;
   col = num % maxPerRow;
   num++;
}
void report() {
   System.out.print( " " + row + col );
}  }

public class FlyweightDemo {
public static final int ROWS = 6, COLS = 10;

public static void main( String[] args ) {
   Gazillion[][] matrix = new Gazillion[ROWS][COLS];
   for (int i=0; i < ROWS; i++)
      for (int j=0; j < COLS; j++)
         matrix[i][j] = new Gazillion( COLS );
   for (int i=0; i < ROWS; i++) {
      for (int j=0; j < COLS; j++)
         matrix[i][j].report();
      System.out.println();
}  }  }