设计模式之GOF23迭代器模式

迭代器模式Iterator

/**
 * 自定义迭代器接口
 * @author 小帆敲代码
 *
 */
public interface MyIterator {
  void first();//游标置于第一个
  void last();//游标置于最后一个
  
  boolean isfirst();
  boolean isLast();
  
  void next();//游标后移一个
  boolean hasNext();//是否有下一个
  
  Object getCurrentObj();//获得当前对象
}

/**
 * 具体聚合类
 * @author 51104
 *
 */
public class ConcreteAggregation {
  private List<Object> list=new ArrayList<Object>();

  public List<Object> getList() {
   return list;
  }

  public void setList(List<Object> list) {
   this.list = list;
  }
  public void addObj(Object obj) {
   list.add(obj);
  }
  public void removeObj(Object obj) {
   list.remove(obj);
  }
  public MyIterator getMyIterator() {
   return new ConcreteIterator();
  }
  //内部类可以使用外部属性
  private class ConcreteIterator implements MyIterator{
   private int cursor;
   @Override
   public void first() {
    cursor=0;
   }

   @Override
   public void last() {
    cursor=list.size()-1;
   }

   @Override
   public boolean isfirst() {
    return cursor==0?true:false;
   }

   @Override
   public boolean isLast() {
    return cursor==(list.size()-1)?true:false;
   }

   @Override
   public void next() {
     if(cursor<list.size()) {
      cursor+=1;
     }
   }

   @Override
   public boolean hasNext() {
    if(cursor==list.size())
     return false;
    return true;
   }

   @Override
   public Object getCurrentObj() {
    return list.get(cursor);
   }
   
  }
}

public class Client {
  public static void main(String[] args) {
   ConcreteAggregation ca=new ConcreteAggregation();
   ca.addObj("aa");
   ca.addObj("bb");
   ca.addObj("cc");
   
   MyIterator mi=ca.getMyIterator();
   while(mi.hasNext()) {
    System.out.println(mi.getCurrentObj());
    mi.next();
   }
  }
}