java学习笔记-设计模式17(迭代器模式)

意图

　　提供一种方法顺序访问一个聚合对象中各个元素, 而又不需暴露该对象的内部表示。

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());
}
}
}

　　

　　转自：http://blog.csdn.net/zhangerqing/article/details/8243942