package innerclasses;

/**

* RUN:

* javac innerclasses/Sequence.java && java innerclasses.Sequence

* OUTPUT:

* 0 1 2 3 4 5 6 7 8 9

*/

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;

public boolean end() {

return i == items.length; // using private field "items" of outer class !

}

public Object current() {

return items[i]; // using private field "items" of outer class !

}

public void next() {

if (i < items.length) { // using private field "items" of outer class !

i++;

}

}

}

public Selector getSelector() {

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.getSelector();

while ( ! selector.end()) {

System.out.print(selector.current() + " ");

selector.next();

}

}

}

interface Selector {

boolean end();

Object current();

void next();

}