jas.space
Class ObjVirtualGrid

java.lang.Object
  java.util.AbstractCollection
      jas.space.Grid
          jas.space.ObjVirtualGrid

All Implemented Interfaces:

IObjGrid, java.lang.Iterable, java.util.Collection

public class ObjVirtualGrid
extends Grid
implements IObjGrid

A sparse bidimensional grid containing one object per cell. This object must be used when the ratio between the size of the grid and its average fullness is high. For instance, if you have a grid of 1000 x 1000, with 1000000 of cells and it has to contain 1000 objects, the better solution for memory occupation is to use an ObjVirtualGrid. Obviuosly the ObjVirtualGrid is slower than ObjGrid, but it is much cheaper in memory occupation.

Title: JAS

Description: Java Agent-based Simulation library

Copyright (C) 2002 Michele Sonnessa

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.

Author:

Michele Sonnessa

Constructor Summary

ObjVirtualGrid(Grid grid)
Create a copy of the given grid.

ObjVirtualGrid(int xSize, int ySize)
Create a grid with given size.

Method Summary

boolean	add(java.lang.Object o) Add an object implementing IGridPosition interface to the grid.
boolean	addGridPosition(IGridPosition object) Add an object implementing IGridPosition interface to the grid.
void	clear() Set all cells to the null value.
boolean	contains(java.lang.Object o) Test if given object is contained into the grid.
int	countObjectsAt(int x, int y) Returns the number of objects allocated in cell (x,y).
boolean	equals(java.lang.Object o) Test if o is the same of this.
java.lang.Object	get(int x, int y) Return the object stored at the given position.
GridIterator	gridIterator() Return a GridIterator storing the position of the read value.
java.util.Iterator	iterator() Return a java standard interator for elements in the grid.
boolean	moveGridPosition(IGridPosition object, int destinationX, int destinationY) Move a IGridPosition object from its current position to the specified destination, only if the destination cell is empty.
boolean	remove(java.lang.Object o) Remove the given object from the grid.
boolean	removeGridPosition(IGridPosition object) Remove the IGridPosition object from the grid.
void	set(int x, int y, java.lang.Object obj) Put the given object at the given position.
int	size() Return the number of objects stored into the grid.
void	swapPositions(int x1, int y1, int x2, int y2) Swap the content of the (x1, y1) and (x2, y2) cells of the grid.
java.lang.Object[]	toArray() Return an array of objects stored into the grid.

Methods inherited from class jas.space.Grid

boundX, boundY, getMooreNeighborsPositions, getVonNeumannNeighborsPositions, getXSize, getYSize, reflectX, reflectY, torusX, torusY, toString

Methods inherited from class java.util.AbstractCollection

addAll, containsAll, isEmpty, removeAll, retainAll, toArray

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface jas.space.IObjGrid

boundX, boundY, getXSize, getYSize, reflectX, reflectY, torusX, torusY

Methods inherited from interface java.util.Collection

hashCode

Constructor Detail

ObjVirtualGrid

public ObjVirtualGrid(Grid grid)

Create a copy of the given grid.

Parameters:

grid - The source grid.

ObjVirtualGrid

public ObjVirtualGrid(int xSize,
                      int ySize)

Create a grid with given size.

Parameters:

xSize - The width of the grid.

ySize - The height of the grid.

Method Detail

add

public boolean add(java.lang.Object o)

Add an object implementing IGridPosition interface to the grid. If object implements IGridPosition it stored in the right position of the grid.

Specified by:

add in interface java.util.Collection

Overrides:

add in class java.util.AbstractCollection

Parameters:

o - The IGridPosition object to be added.

Returns:

True if object was added. If o does not implement IGridPosition interface it will not be added and method will return false.

addGridPosition

public boolean addGridPosition(IGridPosition object)

Add an object implementing IGridPosition interface to the grid. If the destination cell is already occupied the method return false and the object is not added.

Specified by:

addGridPosition in interface IObjGrid

Parameters:

object - The IGridPosition object to be added.

Returns:

True if object has been added. False if destination cell is already occupied or if argument object is null.

clear

public void clear()

Set all cells to the null value.

Specified by:

clear in interface java.util.Collection

Specified by:

clear in class Grid

contains

public boolean contains(java.lang.Object o)

Test if given object is contained into the grid.

Specified by:

contains in interface java.util.Collection

Overrides:

contains in class java.util.AbstractCollection

Parameters:

o - The object to be tested.

Returns:

True if object is present into the grid.

countObjectsAt

public int countObjectsAt(int x,
                          int y)

Description copied from class: Grid

Returns the number of objects allocated in cell (x,y).

Specified by:

countObjectsAt in interface IObjGrid

Specified by:

countObjectsAt in class Grid

Parameters:

x - The x coordinate.

y - The y coordinate.

equals

public boolean equals(java.lang.Object o)

Test if o is the same of this. There is no content comparing.

Specified by:

equals in interface java.util.Collection

Overrides:

equals in class Grid

Parameters:

o - The object to be compared.

Returns:

True o is this object.

get

public java.lang.Object get(int x,
                            int y)

Return the object stored at the given position.

Specified by:

get in class Grid

Parameters:

x - The x coordinate.

y - The y coordinate.

Returns:

The requested object.

gridIterator

public GridIterator gridIterator()

Return a GridIterator storing the position of the read value.

Overrides:

gridIterator in class Grid

Returns:

A GridIterator that scrolls grid from the top-left corner to the bottom-right, reading each line from left to right. It remember the position of the last read value.

iterator

public java.util.Iterator iterator()

Description copied from class: Grid

Return a java standard interator for elements in the grid.

Specified by:

iterator in interface java.lang.Iterable

Specified by:

iterator in interface java.util.Collection

Overrides:

iterator in class Grid

Returns:

A iterator that scrolls grid from the top-left corner to the bottom-right, reading each line from left to right.

moveGridPosition

public boolean moveGridPosition(IGridPosition object,
                                int destinationX,
                                int destinationY)

Move a IGridPosition object from its current position to the specified destination, only if the destination cell is empty.

Specified by:

moveGridPosition in interface IObjGrid

Parameters:

destinationX - The x destination coordinate.

destinationY - The y destination coordinate.

object - An object implementing IGridPosition interface.

Returns:

true if object has been moved, false otherwise.

remove

public boolean remove(java.lang.Object o)

Remove the given object from the grid.

Specified by:

remove in interface java.util.Collection

Overrides:

remove in class java.util.AbstractCollection

Parameters:

o - The object to be removed.

Returns:

True if object was found and removed, false otherwise.

Throws:

java.lang.ClassCastException - If o does not implement IGridPosition interface.

removeGridPosition

public boolean removeGridPosition(IGridPosition object)

Remove the IGridPosition object from the grid.

Specified by:

removeGridPosition in interface IObjGrid

Parameters:

object - The IGridPosition object to be removed.

Returns:

true if object has been removed. False if object is null or is not present on the grid.

set

public void set(int x,
                int y,
                java.lang.Object obj)

Put the given object at the given position.

Specified by:

set in class Grid

Parameters:

x - The x coordinate.

y - The y coordinate.

obj - The object to be stored at the (x, y) cell.

size

public int size()

Return the number of objects stored into the grid.

Specified by:

size in interface java.util.Collection

Specified by:

size in class Grid

Returns:

The sum of cells containing an object.

swapPositions

public void swapPositions(int x1,
                          int y1,
                          int x2,
                          int y2)

Swap the content of the (x1, y1) and (x2, y2) cells of the grid.

Specified by:

swapPositions in class Grid

Parameters:

x1 - The x coordinate for the first cell.

y1 - The y coordinate for the first cell.

x2 - The x coordinate for the second cell.

y2 - The y coordinate for the second cell.

toArray

public java.lang.Object[] toArray()

Return an array of objects stored into the grid.

Specified by:

toArray in interface java.util.Collection

Overrides:

toArray in class java.util.AbstractCollection

Returns:

A vector containing only the objects stored into the grid. The empty cells are ignored.