编写程序展示一个学校院系结构：一个学校中有多个院，一个学院中有多个系
效果图:
使用迭代器模式进行遍历，将数据的存储和数据的遍历进行分离
1.uml
2.代码一览
//1.提供数据源
package com.liz.GOF23.iterator.college;
//数据元(数据元素)
public class Department {
private String name;
//描述
private String desc;
public String getName() {
return name;
}
public Department(String name, String desc) {
this.name = name;
this.desc = desc;
}
public void setName(String name) {
this.name = name;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
}
//！！ 注:抽象迭代器Iterator在系统中已经提供，无需自己手动编写，直接实现接口即可
//具体迭代器，定义了以List形式存储的遍历思路
//此处以List方式存放Department
public class InfoCollegeIterator implements Iterator {
List<Department> departmentList;
int index = -1;//索引
//构造器 => 内部注入Department
public InfoCollegeIterator(List<Department> departmentList){
this.departmentList = departmentList;
}
//判断集合中还有没有下一个元素
@Override
public boolean hasNext() {
if(index >= departmentList.size() - 1){
return false;
}else{
index +=1;//由于起始点是 -1
return true;
}
}
@Override
public Object next() {
return departmentList.get(index);
}
//空实现remove方法
public void remove(){
}
}
//具体迭代器，定义了以数组形式存储的遍历思路
//此处以数组方式存放Department
public class ComputerCollegeIterator implements Iterator {
Department[] departments;
int position = 0;//遍历的位置
//将数据注入迭代器
public ComputerCollegeIterator(Department[]departments){
this.departments = departments;
}
//判断是否还有下一个
@Override
public boolean hasNext() {
if(position >= departments.length || departments[position] == null){
return false;
}else{
return true;
}
}
@Override
public Object next() {
Department department = departments[position];
position+=1;//后移一位
return department;
}
@Override
public void remove() {
//暂时不需要删除方法 默认实现..
}
}
注: 以上代码已经将迭代器实现完毕，接下来实现数据的存储以及将迭代器放入到聚合角色中
//抽象聚合（内部具体实现了对数据的初始化，同时获取迭代器）
public interface College {
public String getName();
//增加系的方法
public void addDepartment(String name,String desc);
//返回一个迭代器,遍历
public Iterator createIterator();
}
//具体聚合1
public class ComputerCollege implements College {
//数据在此处以 数组形式存储
Department[] departments;
int numOfDepartment = 0;//保存当前数组的对象个数
@Override
public String getName() {
return "计算机学院";
}
//init_data
public ComputerCollege(){
departments = new Department[5];
addDepartment("java","java专业");
addDepartment("php","php专业");
addDepartment("c","c专业");
addDepartment("c++","c++专业");
addDepartment("python","python专业");
}
@Override
public void addDepartment(String name, String desc) {
//真正的数据
Department department = new Department(name, desc);
departments[numOfDepartment] = department;
numOfDepartment+=1;
}
//获取一个迭代器对象
@Override
public Iterator createIterator() {
return new ComputerCollegeIterator(departments);
}
}
//具体聚合2
public class InfoCollege implements College {
//数据在此处以列表形式存储
List<Department> departmentList;
public InfoCollege(){
departmentList = new ArrayList<Department>();
addDepartment("信息安全","信息安全专业");
addDepartment("网络安全","网络安全专业");
addDepartment("服务器安全","服务器安全专业");
}
@Override
public String getName() {
return "信息工程学院";
}
@Override
public void addDepartment(String name, String desc) {
Department department = new Department(name,desc);
departmentList.add(department);
}
//获取迭代器对象
@Override
public Iterator createIterator() {
return new InfoCollegeIterator(departmentList);
}
}
注:在具体聚合中，注意createIterator（）方法，内部实例化具体的迭代器对象。
此方法将迭代器对象绑定入聚合对象，同时，迭代器对象可以操作聚合对象内部的数据
（设计的过于巧妙了…）
//输出所有的信息（遍历细节）
public class OutPut {
//学院集合
List<College> collegeList;
public OutPut(List<College> collegeList){
this.collegeList = collegeList;
}
//遍历所有的学院，调用printDepartment输出各个学院的系
public void printCollege(){
//从college中取出所有的学院，java中List已经实现了iterator
Iterator<College> iterator = collegeList.iterator();
while(iterator.hasNext()){
//取出一个学院
College c = iterator.next();
//输出学院的名称
System.out.println("学院名称:"+c.getName());
//打印系信息
printDepartment(c.createIterator());//得到对应的迭代器
System.out.println("-------------------------");
}
}
//输出信息(系)
public void printDepartment(Iterator iterator){
while(iterator.hasNext()){
//从list0开始向后遍历
Department d = (Department) iterator.next();
System.out.println("系名称:"+d.getName());
System.out.println("系描述:"+d.getDesc());
}
}
}
//client
public static void main(String[] args) {
//创建学院
List<College> collegeList = new ArrayList<>();
ComputerCollege computerCollege = new ComputerCollege();
InfoCollege infoCollege = new InfoCollege();
//调整注入的数据
collegeList.add(computerCollege);
collegeList.add(infoCollege);
OutPut outPut = new OutPut(collegeList);
outPut.printCollege();
}
}
输出结果:
注:可以调整client中的注入的数据，从而实现不同形式的遍历
优点:
缺点: 每一个聚合对象都需要一个迭代器，导致生成多个迭代器不好管理类。
参考资料: 韩顺平java设计模式