迭代器模式提供一种方法访问一个容器对象中各个元素，而又不需暴露该对象的内部细节。
设计模式，一定要敲代码理解
抽象迭代器
/*** 迭代抽象* */
public interface Iterator<A> {A next();boolean hasNext();
}
迭代器实现
/*** @author ggbond* @date 2024年04月13日 09:08*/
public class MyIterator<T> implements Iterator<T>{private MyCollection<T> myCollection;private int size;private int index; //索引游标public MyIterator(MyCollection<T> myCollection) {this.myCollection = myCollection;this.index = 0;this.size = myCollection.getSize();}@Overridepublic T next() {if (index < size) {return myCollection.getNext(index++);}return null;}@Overridepublic boolean hasNext() {return index < size;}
}
抽象集合
/*** 定义集合* */
public interface Collection<A> {boolean add(A a);boolean remove(A a);Iterator<A> createIterator();}
集合实现
/*** @author ggbond* @date 2024年04月13日 09:12*/
public class MyCollection<T> implements Collection<T>{private ArrayList<T> list=new ArrayList<T>();public int getSize() {return list.size();}@Overridepublic boolean add(T t) {return list.add(t);}@Overridepublic boolean remove(T t) {return list.remove(t);}@Overridepublic Iterator createIterator() {return new MyIterator(this);}public T getNext(int i) {return list.get(i);}
}
迭代对象
/*** @author ggbond* @date 2024年04月13日 09:29*/
public class Person {String name;String cardID;public Person(String name, String cardID) {this.name = name;this.cardID = cardID;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getCardID() {return cardID;}public void setCardID(String cardID) {this.cardID = cardID;}@Overridepublic String toString() {return "Person{" +"name='" + name + '\'' +", cardID='" + cardID + '\'' +'}';}
}
测试与结果
public class Main {public static void main(String[] args) {Person p1= new Person("ggbond1","001");Person p2= new Person("ggbond2","002");Person p3= new Person("ggbond3","003");Person p4= new Person("ggbond4","004");Collection<Person> collection=new MyCollection<>();collection.add(p1);collection.add(p2);collection.add(p3);collection.add(p4);Iterator<Person> iterator = collection.createIterator();while (iterator.hasNext()) {System.out.println(iterator.next());}}
}
Person{name='ggbond1', cardID='001'}
Person{name='ggbond2', cardID='002'}
Person{name='ggbond3', cardID='003'}
Person{name='ggbond4', cardID='004'}
总结
迭代器模式将数据存储和数据遍历的职责进行分离。但针对不同结构的迭代对象，迭代方式需进行添加。
代码下载
代码下载
