Notes

public class CallZone
{
private String name;

private static Set<CallZone> allZones = new HashSet<CallZone>();

/**
* The call zone for Canada.
*/
public static final CallZone CANADA = new CallZone("CANADA");

/**
* The call zone for the United States.
*/
public static final CallZone USA = new CallZone("USA");

/**
* The call zone for Europe.
*/
public static final CallZone EUROPE = new CallZone("EUROPE");

/**
* The call zone for Asia.
*/
public static final CallZone ASIA = new CallZone("ASIA");

/**
* The call zone for Australia and New Zeland.
*/
public static final CallZone ANZ = new CallZone("ANZ");

/**
* The call zone for Latin America.
*/
public static final CallZone LATINAM = new CallZone("LATINAM");

/**
* The call zone for Africa.
*/
public static final CallZone AFRICA = new CallZone("AFRICA");

private CallZone(String name)
{
this.name = name;
CallZone.allZones.add(this);
}

/**
* Produces the set of all valid call zones.
*
* @return the set of all valid call zones.
*/
public static Set<CallZone> getAllZones()
{
return new HashSet<CallZone>(CallZone.allZones);
}

/**
* Creates a string representation of the object; the call zone's name is returned.
*
* @return the string representation of the object.
*/
@Override
public String toString()
{
return this.name;
}

/**
* Creates a hash code for the object, which is the hash code of the string
* that is the call zone's name.
*
* @return the object's hash code.
*/
@Override
public int hashCode()
{
return this.toString().hashCode();
}

/**
* Indicates whether some other object is "equal to" this one.
* The result is true if and only if the argument is not null, is a call zone,
* and both objects have the same name.
*
* @param obj The object to compare with.
* @return true if the call zones' names are equal; false otherwise.
*/
@Override
public boolean equals(Object obj)
{
boolean eq = false;
if(obj != null && this.getClass() == obj.getClass())
{
CallZone other = (CallZone) obj;
eq = this.toString().equals(other.toString());
}
return eq;
}
}