图解Java设计模式之迭代器模式

package com.example.demo.iterator;

import java.util.Iterator;

import javax.swing.text.Position;

public class ComputerCollegeIterator implements Iterator{
	
	// 这里我们需要Department 是以怎样的方式存放
	private Department[] departments;
	// 遍历的位置
	private int position = 0;

	public ComputerCollegeIterator(Department[] departments) {
		super();
		this.departments = departments;
	}

	/**
	 * 判断是否还有下一个元素
	 */
	@Override
	public boolean hasNext() {
		// TODO Auto-generated method stub
		if (departments.length <= position || departments[position] == null) {
			return false;
		}
		return true;
	}

	@Override
	public Object next() {
		// TODO Auto-generated method stub
		Department department = departments[position];
		position += 1;
		return department;
	}

}
package com.example.demo.iterator;

import java.util.Iterator;
import java.util.List;

public class InfoColleageIterator implements Iterator{
	
	/**
	 * 信息工程学院是以list方式存放系
	 */
	private List<Department> departmentList;
	
	/**
	 * 索引
	 */
	private int index = -1;
	
	public InfoColleageIterator(List<Department> departmentList) {
		super();
		this.departmentList = departmentList;
	}

	/**
	 * 判断list中还有没有下一个元素
	 */
	@Override
	public boolean hasNext() {
		// TODO Auto-generated method stub
		if (index >= departmentList.size() - 1) {
			return false;
		}
		index += 1;
		return true;
	}

	@Override
	public Object next() {
		// TODO Auto-generated method stub
		return departmentList.get(index);
	}
	
	/**
	 * remove空实现
	 */
	public void remove() {
		
	}

}
package com.example.demo.iterator;

/**
 * 系
 * @author zhaozhaohai
 *
 */
public class Department {
	
	private String name;
	
	private String desc;

	public Department(String name, String desc) {
		super();
		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;
	}
	
	

}
package com.example.demo.iterator;

import java.util.Iterator;

public interface College {
	
	public String getName();
	
	/**
	 * 增加系的方法
	 * @param name
	 * @param desc
	 */
	public void addDepartment(String name, String desc);
	
	/**
	 * 返回一个迭代器，遍历
	 * @return
	 */
	public Iterator createIterator();

}
package com.example.demo.iterator;

import java.util.Iterator;

public class ComputerCollege implements College{
	
	private Department[] departments;
	// 保持当前数组的对象个数
	private int numOfDepartment = 0;
	
	public ComputerCollege() {
		departments = new Department[5];
		addDepartment("java", "java");
		addDepartment("前端", "前端");
		addDepartment("大数据", "大数据");
	}

	@Override
	public String getName() {
		// TODO Auto-generated method stub
		return "计算机学院";
	}

	@Override
	public void addDepartment(String name, String desc) {
		// TODO Auto-generated method stub
		Department department = new Department(name, desc);
		departments[numOfDepartment] = department;
		numOfDepartment += 1;
	}

	@Override
	public Iterator createIterator() {
		// TODO Auto-generated method stub
		return new ComputerCollegeIterator(departments);
	}

}
package com.example.demo.iterator;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class InfoCollege implements College{
	
	private List<Department> departmentList;
	
	public InfoCollege() {
		departmentList = 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");
		addDepartment("工程安全专业", "工程安全专业");
	}

	@Override
	public String getName() {
		// TODO Auto-generated method stub
		return "信息工程学院";
	}

	@Override
	public void addDepartment(String name, String desc) {
		// TODO Auto-generated method stub
		Department department = new Department(name, desc);
		departmentList.add(department);
	}

	@Override
	public Iterator createIterator() {
		// TODO Auto-generated method stub
		return new InfoColleageIterator(departmentList);
	}

}
package com.example.demo.iterator;

import java.util.Iterator;
import java.util.List;

public class OutPutImpl {
	
	
	// 学院集合
	private List<College> colleges;
	
	public OutPutImpl(List<College> colleges) {
		super();
		this.colleges = colleges;
	}
	
	/**
	 * 遍历所有学院，然后调用printDepartment 输出各个学院的系
	 */
	public void printCollege() {
		// 从collegeList 取出所有学院，Java中的list 已经实现Iterator
		Iterator iterator = colleges.iterator();
		while (iterator.hasNext()) {
			// 取出一个学院
			College college = (College) iterator.next();
			System.out.println("====" + college.getName() + "====");
			printDepartment(college.createIterator());
		}
	}

	/**
	 * 输出学院里的系
	 * @param iterator
	 */
	public void printDepartment(Iterator iterator) {
		while (iterator.hasNext()) {
			Department department = (Department)iterator.next();
			System.out.println(department.getName());
		}
	}

}
package com.example.demo.iterator;

import java.util.ArrayList;
import java.util.List;

public class Client {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		// 创建学院
		List<College> colleges = new ArrayList<College>();
		ComputerCollege college = new ComputerCollege();
		InfoCollege infoCollege = new InfoCollege();
		colleges.add(college);
		//colleges.add(infoCollege);
		OutPutImpl outPutImpl = new OutPutImpl(colleges);
		outPutImpl.printCollege();
	}

}