文檔查閱說明:
定義:它提供一種方法訪問一個容器對象中各個元素,而又不需暴露該對象的內部細節
使用場景:
● 訪問一個聚合對象的內容而無須暴露它的內部表示;
● 需要爲聚合對象提供多種遍歷方式;
● 爲遍歷不同的聚合結構提供一個統一的接口
注意事項:迭代器模式就是分離了集合對象的遍歷行爲,抽象出一個迭代器類來負責,這樣既可以做到不暴露集合的內部結構,又可讓外部代碼透明地訪問集合內部的數據
ps:迭代器模式已經被淘汰,java中已經把迭代器運用到各個聚集類(collection)中了,使用java自帶的迭代器就已經滿足我們的需求了
public abstract class Iterator {
public abstract Object first();
public abstract Object next();
public abstract boolean hasNext();
public abstract Object getCurrentItem();
}
public abstract class Aggregate {
public abstract Iterator createIterator();
}
public class ConCreateAggregate extends Aggregate{
private List<Object> items = new ArrayList<Object>();
@Override
public Iterator createIterator() {
return new ConCreateIterator(this);
}
public int count() {
return items.size();
}
public void add(Object name) {
items.add(name);
}
public Object get(int index) {
return items.get(index);
}
}
public class ConCreateIterator extends Iterator {
private ConCreateAggregate aggregate;
private int current = 0;
public ConCreateIterator(ConCreateAggregate aggregate) {
super();
this.aggregate = aggregate;
}
@Override
public Object first() {
return aggregate.get(0);
}
@Override
public Object next() {
if(current < aggregate.count()) {
return aggregate.get(current++);
}else {
return null;
}
}
@Override
public boolean hasNext() {
return current < aggregate.count();
}
@Override
public Object getCurrentItem() {
return aggregate.get(current);
}
}
public class Test {
public static void main(String[] args) {
ConCreateAggregate aggregate = new ConCreateAggregate();
aggregate.add("芒果柒");
aggregate.add("蘋果八");
aggregate.add("榴蓮一");
Iterator iterator = new ConCreateIterator(aggregate);
while(iterator.hasNext()) {
System.out.println("水果排名:"+iterator.next());
}
}
}