一篇文章掌握迭代器模式
作者:互联网
一.案例引入
具体描述
之前用组合模式解决过这个问题,这次针对遍历。
二.迭代器模式
1.基本介绍
2.原理类图
解释
3.迭代器模式解决上述问题的UML类图
4.具体代码
College
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
public Iterator createIterator();
}
Department
//系
public class Department {
private String name;
private String desc;
public Department(String name, String desc) {
this.name = name;
this.desc = desc;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
}
ComputerCollegeIterator
public class ComputerCollegeIterator implements Iterator {
//这里我们需要知道Department是以怎么样的方式存放
Department[] departments;
int position = 0;//遍历的位置
public ComputerCollegeIterator(Department[] departments) {
this.departments = departments;
}
@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;
return department;
}
public void remove(){
}
}
InfoCollegeIterator
public class InfoCollegeIterator implements Iterator {
//信息工程学院是以List方式存放
List<Department> departments;
int index = -1;
public InfoCollegeIterator(List<Department> departments) {
this.departments = departments;
}
@Override
public boolean hasNext() {
if(index >= departments.size() -1){
return false;
}else {
index += 1;
return true;
}
}
@Override
public Object next() {
return departments.get(index);
}
public void remove(){}
}
ComputerCollege
public class ComputerCollege implements College{
Department[] departments;
int numOfDepartment = 0;//保存当前数组的对象个数
public ComputerCollege(){
departments = new Department[5];
addDepartment("Java专业","Java专业");
addDepartment("Python专业","Python专业");
}
@Override
public String getName() {
return "计算机学院";
}
@Override
public void addDepartment(String name, String desc) {
Department department = new Department(name, desc);
departments[numOfDepartment] = department;
numOfDepartment += 1;
}
@Override
public Iterator createIterator() {
return new ComputerCollegeIterator(departments);
}
}
InfoCollege
public class InfoCollege implements College{
List<Department> departments;
public InfoCollege(){
departments = new ArrayList<Department>();
addDepartment("信息安全专业","信息安全专业");
addDepartment("网络安全专业","网络安全专业");
}
@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);
departments.add(department);
}
@Override
public Iterator createIterator() {
return new InfoCollegeIterator(departments);
}
}
OutPutImpl
public class OutPutImpl {
//学院集合
List<College> colleges;
public OutPutImpl(List<College> colleges) {
this.colleges = colleges;
}
//输出
//遍历所有学院,然后调用printDepartment输出各个学院的系
public void printCollege(){
//从colleges去除所有学院,Java中的List已经实现Iterator
Iterator<College> iterator = colleges.iterator();
while (iterator.hasNext()){
//取出一个学院
College next = iterator.next();
System.out.println(next.getName());
printDepartment(next.createIterator());//得到对应的迭代器
}
}
//先解决学院输出系的问题
public void printDepartment(Iterator iterator){
while (iterator.hasNext()){
Department next = (Department)iterator.next();
System.out.println(next.getName());
}
}
}
Client
public class Client {
public static void main(String[] args) {
//创建学院
List<College> colleges = new ArrayList<>();
ComputerCollege computerCollege = new ComputerCollege();
InfoCollege infoCollege = new InfoCollege();
colleges.add(computerCollege);
colleges.add(infoCollege);
OutPutImpl outPut = new OutPutImpl(colleges);
outPut.printCollege();
}
}
计算机学院
Java专业
Python专业
信息工程学院
信息安全专业
网络安全专业
5.优缺点分析
标签:String,迭代,departments,name,文章,Department,desc,public,一篇 来源: https://blog.csdn.net/afdafvdaa/article/details/113921058