Map集合

import java.util.*;

class  Student implements Comparable
{
	private int id;
	private String name;
	public int getId(){
		return id;
	}
	public String getName(){
		return name;
	}
	
	public Student(int id,String name){
		this.id = id;
		this.name = name;
	}
	//当直接打印Student时，或显示 id和name
	public String toString(){
		return id+"......"+name;
	}
	
	//如果用Hash表 装 数据就重写 hashCode和equals两方法
	public int hashCode(){
		return name.hashCode()+id*34;
	}
	public boolean equals(Object o){
		if(!(o instanceof Student)){
			//throw new RuntimeException("类型不匹配");
			throw new ClassCastException("类型不匹配");
		}

		Student s = (Student)o;
		return this.name.equals(s.name) && this.id==s.id;
	}

	//如果是二叉树 就得 重写 compareTo方法(那么就得实现Comparable接口)
	public int compareTo(Object o){
		if(!(o instanceof Student)){
			//throw new RuntimeException("类型不匹配");
			throw new ClassCastException("类型不匹配");
		}
		Student s = (Student)o;
		int num = new Integer(this.id).compareTo(s.id);
		if(num == 0)
			return this.name.compareTo(s.name);
		return num;	
	}

	
}

class MapTest
{
	public static void main(String[] args) 
	{
		//显示 map 与 list 嵌套
		//showMap_and_List();
		//显示 map 与 map 嵌套
		showMap_and_Map();
	}
	//显示 map 与 list 嵌套
	public static void showMap_and_List(){
		HashMap<String,List<Student>> czbk = new HashMap<String,List<Student>>();
		List<Student> first = new ArrayList<Student>();
		List<Student> second = new ArrayList<Student>();
		czbk.put("预热班",first);
		czbk.put("就业班",second);

		first.add(new Student(1, "张三"));
		first.add(new Student(2, "李四"));
		first.add(new Student(3, "王五"));
		first.add(new Student(4, "赵六"));

		second.add(new Student(1, "zhang"));
		second.add(new Student(2, "li"));
		second.add(new Student(3, "wang"));
		second.add(new Student(4, "liu"));
	
		Set<String> keySet = czbk.keySet();
		Iterator<String> it = keySet.iterator();
		while(it.hasNext()){
			String key = it.next();
			List<Student> list = czbk.get(key);
			getStudent(list);
		}
	}
	public static void getStudent(List<Student> list){
		Iterator<Student> it = list.iterator();
		while(it.hasNext()){
			Student stu = it.next();
			System.out.println(stu);
		}
	}

	//显示 map 与 map 嵌套
	public static void showMap_and_Map(){
		//map集合key不能为 int 类型，但是可以包装为 Integer 类型
		HashMap<String,HashMap<Integer,String>> czbk = new HashMap<String,HashMap<Integer,String>>();
		HashMap<Integer,String> first = new HashMap<Integer,String>();
		HashMap<Integer,String> second = new HashMap<Integer,String>();
		czbk.put("预热班",first);
		czbk.put("就业班",second);

		first.put(1, "张三");
		first.put(2, "李四");
		first.put(3, "王五");
		first.put(4, "赵六");

		second.put(1, "zhang");
		second.put(2, "li");
		second.put(3, "wang");
		second.put(4, "liu");
		
		Set<Map.Entry<String,HashMap<Integer,String>>> entrySet = czbk.entrySet();
		Iterator<Map.Entry<String,HashMap<Integer,String>>> it =  entrySet.iterator();
		while(it.hasNext()){
			Map.Entry<String,HashMap<Integer,String>> me = it.next();
			String key = me.getKey();
			HashMap<Integer,String> hm = me.getValue();
			System.out.println(key+"........"+hm);
			getStudent1(hm);
		}
	}
	public static void getStudent1(HashMap<Integer,String> hashMap){
		Set<Map.Entry<Integer,String>> entrySet = hashMap.entrySet();
		Iterator<Map.Entry<Integer,String>> it = entrySet.iterator();
		while(it.hasNext()){
			Map.Entry<Integer,String>  me = it.next();
			int key = me.getKey();
			String value = me.getValue();
			System.out.println(key +"..........."+ value);
		}
	}
	
}