com.sun.tv.si.ServiceIteratorImpl Maven / Gradle / Ivy
/*
* @(#)ServiceIterator.java 1.10 00/07/03
*
* Copyright 1998-2000 by Sun Microsystems, Inc.,
* 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
* All rights reserved.
*
* This software is the confidential and proprietary information
* of Sun Microsystems, Inc. ("Confidential Information"). You
* shall not disclose such Confidential Information and shall use
* it only in accordance with the terms of the license agreement
* you entered into with Sun.
*/
package com.sun.tv.si;
import java.util.*;
import javax.tv.service.navigation.*;
import java.util.NoSuchElementException;
import javax.tv.service.Service;
/**
* ServiceIterator permits iteration over an ordered
* list of Service objects. Applications may use the
* ServiceIterator interface to browse a
* ServiceList forward or backward.
*
* Upon initial usage, hasPrevious() will return
* false and nextService() will return the
* first Service in the list, if present.
*
* @see ServiceList */
public class ServiceIteratorImpl implements ServiceIterator {
int theIndex;
Vector services;
/**
*
*/
public ServiceIteratorImpl(Vector list) {
if(list != null) {
services = list;
} else {
services = new Vector();
}
theIndex = -1;
}
/**
*
* Resets the iterator to the beginning of the list, such that
* hasPrevious returns false.
*
* */
public void toBeginning() {
theIndex = -1;
}
/**
*
* Sets the iterator to the end of the list, such that
* hasNext returns false.
*/
public void toEnd() {
theIndex = services.size();
}
/**
*
* Reports the next Service object in the list. This
* method may be called repeatedly to iterate through the list.
*
* @return The Service object at the next position in
* the list.
*
* @throws NoSuchElementException If the iteration has no next
* Service.
*/
public Service nextService() {
if (hasNext() == false) {
String msg = "next index (" + theIndex + ") is out of range.";
throw new NoSuchElementException(msg);
}
theIndex++;
return (Service)services.elementAt(theIndex);
}
/**
*
* Reports the previous Service object in the list.
* This method may be called repeatedly to iterate through the list
* in reverse order.
*
* @return The Service object at the previous position
* in the list.
*
* @throws NoSuchElementException If the iteration has no previous
* Service.
*/
public Service previousService() {
if (hasPrevious() == false) {
String msg = "next index (" + theIndex + ") is out of range.";
throw new NoSuchElementException(msg);
}
theIndex--;
return (Service)services.elementAt(theIndex);
}
/**
* Tests if there is a Service in the next position in
* the list.
*
* @return true if there is a Service in
* the next position in the list; false otherwise.
*/
public boolean hasNext() {
int index = theIndex + 1;
return !(index < 0 || index > services.size() - 1);
}
/**
*
* Tests if there is a Service in the previous
* position in the list.
*
* @return true if there is a Service in
* the previous position in the list; false otherwise.
*/
public boolean hasPrevious() {
int index = theIndex - 1;
return !(index < 0 || index > services.size() - 1);
}
}