package com.leeue.desingpattern.iterator;import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;/*** 使用迭代器模式* 需求: 假设现在有一个教室类，里面包含了一堆学生。我现在要遍历教室里的学生类。这个时候需要定义自己的教室迭代器** @author liyue* @date 2020-05-19 10:56*/
public class IteratorDemo {/*** 学生类*/public static class Student {private String name;public Student(String name) {this.name = name;}public String getName() {return name;}@Overridepublic String toString() {return "Student [name=" + name + "]";}}/*** 1.定义我们自己的迭代器接口*/public interface MyIterator {/*** 判断是否有下一个元素  抽象类，让子类进行重写。** @return*/abstract boolean hasNext();/*** 返回当前元素** @return*/abstract Object next();}/*** 2.定义需要遍历的集合类，获取需要遍历的集合类的迭代器*/public interface Aggregate {/*** 获取需要遍历的集合类的迭代器。这里我们的需求是遍历学生类。** @return*/abstract Iterator<Student> iterator();}/*** 4.定义教室类*/public static class Classroom implements Aggregate {private List<Student> studentList;//记录教室里的学生的个数private int size = 0;public Classroom(int length) {this.studentList = new ArrayList<Student>(2);}/*** 根据下标获取学生** @param index* @return*/public Student getStudent(int index) {return studentList.get(index);}/*** 往教室类中添加学生** @param student*/public void addStudent(Student student) {studentList.add(student);size++;}/*** 获取教室类里面的学生个数** @return*/public int getSize() {return size;}/*** 获取集合类的迭代器  studentList** @return*/public Iterator<Student> iterator() {return studentList.iterator();}}/*** 4.定义教室迭代器*/public static class ClassroomIterator implements MyIterator {private Classroom classroom;private int index;public ClassroomIterator(Classroom classroom) {this.classroom = classroom;this.index = 0;}/*** 假设此时 index 是 0，classroom的size是 2那么肯定是可以获取下一个学生的。* 如果index 是 2，classroom的size也是2，那么classroom已经没有下一个学生了。只能遍历数组下标是 0和1** @return*/public boolean hasNext() {if (index < classroom.getSize()) {return true;}return false;}public Object next() {Student student = classroom.getStudent(index);index++;return student;}}public static void main(String[] args) {Student student1 = new Student("小明");Student student2 = new Student("小米");Classroom classroom = new Classroom(2);classroom.addStudent(student1);classroom.addStudent(student2);//遍历classroom里面的studentIterator<Student> studentIterator = classroom.iterator();while (studentIterator.hasNext()) {System.out.println(studentIterator.next());}/*** 这个是jdk自带的迭代器*/Iterator<Student> sysStudentIterator = classroom.studentList.iterator();while (sysStudentIterator.hasNext()) {System.out.println(sysStudentIterator.next());}}
}

注意: 迭代器模式，现在除非特殊情况下，才会有可能会用到。因为现在jdk自己已经帮你实现了迭代器的功能了。我们大可不必自己去实现迭代器的功能。
上面都是从架构班学习而来进行总结和注释