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;
public boolean end()
{
return i == items.length;
}
public Object current()
{
return items[i];
}
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.println(selector.current() + " ");
selector.next();
}
}
}
内部类自动用用外围对象的访问权
这是因为 当外围对象创建了一个内部对象的时候 内部对象会秘密的捕捉一个指向外围对象的引用 然后在你访问外围对象的成员的时候 就是靠那个引用来访问外围成员