Think in Java - 迭代器设计模式

package packinfo;


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


public class Sequence{
private Object[] items;
private int next = 0;
Sequence(int size){
items = new Object[size];
} 
public void add(Object x) {
if(next < items.length)
{
items[next++] = x;
}
}

public Selector selector()
{
return new SequenceSelector();
}

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 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.println(selector.current() + " ");
selector.next();
}
}
 
}