// SectorList.java

public class SectorList extends List
{
	private int freeSectors; // number of sectors free on disk

	// constructor creates empty list with name
	public SectorList()
	{
		this( 0 );
	} // end constructor

	// constructor
	public SectorList( int num )
	{
		super( "Sector List" );
	} // end constructor


	// set freeSectors
	public void setFreeSectors( int num )
	{
		freeSectors = num >= 0 ? num : 0;
	} // end method


	// get freeSectors
	public int getFreeSectors()
	{
		return freeSectors;
	} // end method getFreeSectors


	// get free space how many sectors available
	public int getFreeSpace()
	{
		ListNode current;
		Sector sec;
		int sectorsFree = 0;

		current = getFirstNode();

		// loop thru entire list and count all the free sectors
		while( current != null )
		{
			sec = ( Sector ) current.getObject();

			if( sec.getFree() ) // sector is free
				sectorsFree++;

			current = current.getNext();
		} // end while

		return sectorsFree;
	} // end method getFreeSpace


	// print available sectors
	public String sectorsAvailable()
	{
		ListNode current;
		Sector sec;
		int size = getFreeSpace();
		String string = "";

		current = getFirstNode();

		// loop thru entire list and count all the free sectors
		while( current != null )
		{
			sec = ( Sector ) current.getObject();

			if( sec.getFree() )
			{
				size--;
				if ( size == 0  ) // last sector to print needs no comma
					string += sec.toString();
				else
					string += sec.toString() + ", ";
			} // end if

			current = current.getNext();
		} // end while

		return string;
	} // end method sectorsAvailable
} // end class List