Exchange.java

interface ExchangeInterface{
	public Exchange parent();
	public Exchange numChildren();
	public Exchange child(int i);
	public Boolean isRoot();
	public RoutingMapTree subtree(int i);
	public MobilePhoneSet residentSet();
}

public class Exchange{
	
	/*
		The nodes of the Routing Map structure.
	*/
	
	Integer id;
	Exchange parent;
	ExchangeList children;
	MobilePhoneSet mobileSet;

	public Exchange(int number){
	/*
		Constructor to create an exchange.
		Unique identifier for an exchange is an integer.
	*/
		id = number;
		children = new ExchangeList();
		mobileSet = new MobilePhoneSet();
	}

	public Integer getUniqueId(){
		return id;
	}

	public void setUniqueId(int i){
		id = i;
	}

	public Exchange parent(){
	// Returns the parent of the Exchange in RoutingMapTree
		return parent;
	}

	public void setParent(Exchange node){
		parent = node;
	}

	public void addMobileToResidentSet(MobilePhone mobile){
		mobileSet.Insert(mobile);
	}

	public void deleteMobilefromResidentSet(MobilePhone mobile) throws MobilePhoneNotFoundException{

		try{
			mobileSet.Delete(mobile);
		}
		catch(NotInSetException e){
			throw new MobilePhoneNotFoundException("Error - No mobile phone with identifer "+mobile.number()+"  found in the network");
		}

	}

	public void addChild(Exchange node){
		node.setParent(this);
		children.add(node);
	}

	public int numChildren(){
	// Number of children
		return children.getSize();
	}

	public Exchange child(int i) throws ChildNotFoundException{

	// Returns the ith child

		int num = numChildren();

		if(i<num && i>=0){

			ExchangeList.Node itr = children.head;

			for(int j=num-1;j>i;j--){
				itr = itr.next;
			}

			return (Exchange)itr.data;

		}

		else{
			throw new ChildNotFoundException("Error - No "+ i +" child of Exchange "+this.getUniqueId());
		}
		
	}

	public MobilePhone searchPhone(int i) throws MobilePhoneNotFoundException{
	// Calls MobilePhoneSet operation searchPhone()
		return mobileSet.searchPhone(i);
	}

	public Boolean isRoot(){
	// Checks if the exchange is a root of a Routing Map Tree.

		if(parent() == null){
			return true;
		}
		return false;

	}

	public RoutingMapTree subtree(int i) throws ChildNotFoundException{
	/*
		Returns the ith subtree.
		Throws exception if the child i is not found.
	*/
		Exchange subtreeAti = child(i);
		RoutingMapTree rmt = new RoutingMapTree();
		rmt.setRoot(subtreeAti);
		return rmt;

	}

	public MobilePhoneSet residentSet(){
	// Returns the resident set of mobile phones of the exchange
        return mobileSet;
    }

    public boolean equals(Exchange o) { 
	/*
    	Two Exchanges are the same 
    	if their identifiers are the same

	*/      
		if (o == this) { 
            return true; 
        } 

        if (!(o instanceof Exchange)) { 
            return false; 
        }  

        return o.getUniqueId() == id; 
    
    }

    public String toString(){
    	// Returns the id of Exchange
    	// In the form of a string
		return String.valueOf(getUniqueId());
    } 

}