Block.java

package jadex.examples.blocksworld;

import jadex.util.SimplePropertyChangeSupport;

import java.awt.*;
import java.beans.PropertyChangeListener;


/**
*  A block in the blocks-world.
*/
public class Block
{
//-------- static part --------

/** The block counter. */
protected static int counter = 0;

//-------- attributes --------

/** The number of the block. */
protected int number;

/** The color of the block. */
protected Color color;

/** The block where this block is located on. */
protected Block lower;

/** The block located on upper of this block. */
protected Block upper;

/** The helper object for bean events. */
public SimplePropertyChangeSupport pcs;

/** The x translation for drawing (0-1). */
protected double dx;

/** The y translation for drawing (0-1). */
protected double dy;

//-------- constructors --------

/**
*  Create a new block.
*  @param color The color of the block.
*  @param lower The block where this block is located on.
*/
public Block(Color color, Block lower)
{
this(++counter, color, lower);
}

/**
*  Create a new block.
*  @param number The number of the block.
*  @param color The color of the block.
*  @param lower The block where this block is located on.
*/
public Block(int number, Color color, Block lower)
{
this.number = number;
this.color = color;
this.pcs = new SimplePropertyChangeSupport(this);
stackOn(lower);
}

//-------- methods --------

/**
*  Get the color of the block.
*  @return The color of the block.
*/
public Color getColor()
{
return color;
}

/**
*  Get the block where this block is located on.
*  @return The block where this block is located on.
*/
public Block getLower()
{
return lower;
}

/**
*  Check if this block is clear.
*/
public boolean isClear()
{
return upper==null;
}

/**
*  Move this block on top of another block.
*/
public void stackOn(Block lower)
{
// Check if block can be moved.
if(!isClear())
{
throw new RuntimeException("Can only move clear blocks: "+this);
}
else if(lower==this)
{
throw new RuntimeException("Cannot move block on itself: "+this);
}

// Remove this block from old lower block.
if(this.lower!=null)
this.lower.removeBlock(this);

// Move to new block.
if(lower!=null)
{
// Check if there is space on block.
if(!lower.isClear())
{
throw new RuntimeException("Can only stack on clear blocks: "+lower);
}
lower.addBlock(this);
this.dx = Math.random();
this.dy = Math.random();
}
setLower(lower);
}

/**
*  Set the lower block, where this block is located on.
*  @param lower The lower block.
*/
protected void setLower(Block lower)
{
Block old = this.lower;
this.lower = lower;
this.pcs.firePropertyChange("lower", old, this.lower);
}

//-------- helper methods --------

/**
*  Add a block to this block.
*/
protected void addBlock(Block block)
{
Block old = this.upper;
this.upper = block;
this.pcs.firePropertyChange("upper", old, this.upper);
}

/**
*  Remove a block from this block.
*/
protected void removeBlock(Block block)
{
this.upper = null;
this.pcs.firePropertyChange("upper", block, null);
}

/**
*  Create a string representation of this block.
*/
public String toString()
{
return "Block "+number;
}

/**
*  Check for equality.
*/
public boolean equals(Object o)
{
return o instanceof Block
&& ((Block)o).number==number
&& ((Block)o).getColor().equals(getColor());
}

//-------- property methods --------

/**
     *  Add a PropertyChangeListener to the listener list.
     *  The listener is registered for all properties.
     *  @param listener  The PropertyChangeListener to be added.
     */
    public void addPropertyChangeListener(PropertyChangeListener listener)
{
pcs.addPropertyChangeListener(listener);
    }

    /**
     *  Remove a PropertyChangeListener from the listener list.
     *  This removes a PropertyChangeListener that was registered
     *  for all properties.
     *  @param listener  The PropertyChangeListener to be removed.
     */
    public void removePropertyChangeListener(PropertyChangeListener listener)
{
pcs.removePropertyChangeListener(listener);
    }

}