// innerclasses/Sequence.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Holds a sequence of Objects

interface Selector {
 boolean end();
 Object current();
 void next();
}

public class Sequence {
 private Object[] items;
 private int next = 0;
 public Sequence(int size) {
 items = new Object[size];
 }
 public void add(Object x) {
 if(next < items.length)
 items[next++] = x;
 }
 private class SequenceSelector implements Selector {
 private int i = 0;
 @Override
 public boolean end() { return i == items.length; }
 @Override
 public Object current() { return items[i]; }
 @Override
 public void next() { if(i < items.length) i++; }
 }
 public Selector selector() {
 return new SequenceSelector();
 }
 public static void main(String[] args) {
 Sequence sequence = new Sequence(10);
 for(int i = 0; i < 10; i++)
 sequence.add(Integer.toString(i));
 Selector selector = sequence.selector();
 while(!selector.end()) {
 System.out.print(selector.current() + " ");
 selector.next();
 }
 }
}
/* Output:
0 1 2 3 4 5 6 7 8 9
*/