详解Java设计模式——迭代器模式

public interface Collection { 
 
 public Iterator iterator(); 
 
 /*取得集合元素*/ 
 public Object get(int i); 
 
 /*取得集合大小*/ 
 public int size(); 
} 
public interface Iterator { 
 //前移 
 public Object previous(); 
 
 //后移 
 public Object next(); 
 public boolean hasNext(); 
 
 //取得第一个元素 
 public Object first(); 
} 

public class MyCollection implements Collection { 
 
 public String string[] = {"A","B","C","D","E"}; 
 @Override 
 public Iterator iterator() { 
 return new MyIterator(this); 
 } 
 
 @Override 
 public Object get(int i) { 
 return string[i]; 
 } 
 
 @Override 
 public int size() { 
 return string.length; 
 } 
} 
public class MyIterator implements Iterator { 
 
 private Collection collection; 
 private int pos = -1; 
 
 public MyIterator(Collection collection){ 
 this.collection = collection; 
 } 
 
 @Override 
 public Object previous() { 
 if(pos > 0){ 
 pos--; 
 } 
 return collection.get(pos); 
 } 
 
 @Override 
 public Object next() { 
 if(pos<collection.size()-1){ 
 pos++; 
 } 
 return collection.get(pos); 
 } 
 
 @Override 
 public boolean hasNext() { 
 if(pos<collection.size()-1){ 
 return true; 
 }else{ 
 return false; 
 } 
 } 
 
 @Override 
 public Object first() { 
 pos = 0; 
 return collection.get(pos); 
 } 
 
} 

public class Test { 
 
 public static void main(String[] args) { 
 Collection collection = new MyCollection(); 
 Iterator it = collection.iterator(); 
 
 while(it.hasNext()){ 
 System.out.println(it.next()); 
 } 
 } 
}