java内部类的例子:链接到外部类[Java编程]

//: Sequence.java
// Holds a sequence of Objects

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

public class Sequence {
  private Object[] o;
  private int next = 0;
  public Sequence(int size) {
    o = new Object[size];
  }
  public void add(Object x) {
    if(next < o.length) {
      o[next] = x;
      next++;
    }
  }
  private class SSelector implements Selector {
    int i = 0;
    public boolean end() {
      return i == o.length;
    }
    public Object current() {
      return o[i];
    }
    public void next() {
      if(i < o.length) i++;
    }
  }
  public Selector getSelector() {
    return new SSelector();
  }
  public static void main(String[] args) {
    Sequence s = new Sequence(10);
    for(int i = 0; i < 10; i++)
      s.add(Integer.toString(i));
    Selector sl = s.getSelector();    
    while(!sl.end()) {
      System.out.println((String)sl.current());
      sl.next();
    }
  }
} ///:~