16_3 map扩展知识

原创于 2021-01-31 19:17:55 发布 · 132 阅读

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该博客展示了如何使用Java的HashMap数据结构来管理教室和学生信息。通过创建一个HashMap来存储教室（key）与对应的学生列表（value），实现了多级映射的概念。每个教室（如“yureban”，“jiuyeban”）关联一个学生列表，列表中包含学生的ID和姓名。博客还提供了遍历HashMap并打印教室及其学生信息的方法，演示了数据结构在实际场景中的应用。

/*
map扩展知识。

map集合被使用是因为具备映射关系。

“yureban” Student(“01” “zhangsan”);

“yureban” Student(“02” “lisi”);

“jiuyeban” “01” “wangwu”;
“jiuyeban” “02” “zhaoliu”;

一个学校有多个教室。每一个教室都有名称。

/
import java.util.;

class Student
{
private String id;
private String name;
Student(String id,String name)
{
this.id = id;
this.name = name;
}
public String toString()
{
return id+":::"+name;
}
}
class MapDemo3
{

public static void demo()
{
	HashMap<String,List<Student>> czbk = new HashMap<String,List<Student>>();

	List<Student> reyu = new ArrayList<Student>();
	List<Student> jiuye = new ArrayList<Student>();

	czbk.put("yureban",reyu);
	czbk.put("jiuyeban",jiuye);

	reyu.add(new Student("01","zhagnsa"));
	reyu.add(new Student("04","wangwu"));
	jiuye.add(new Student("01","zhouqi"));
	jiuye.add(new Student("02","zhaoli"));


	Iterator<String> it = czbk.keySet().iterator();

	while(it.hasNext())
	{
		String roomName = it.next();
		List<Student> room = czbk.get(roomName);
		
		System.out.println(roomName);
		getInfos(room);
	}

	


}
public static void getInfos(List<Student> list)
{
	Iterator<Student> it = list.iterator();
	while(it.hasNext())
	{
		Student s = it.next();
		System.out.println(s);
	}
}




public static void main(String[] args) 
{
	 demo();
	
	/*
	HashMap<String,List<Student>> czbk = new HashMap<String,List<Student>>();

	HashMap<String,String> yure = new HashMap<String,String>();
	
	HashMap<String,String> jiuye = new HashMap<String,String>();

	czbk.put("yureban",yure);
	czbk.put("jiuyeban",jiuye);


	yure.put("01","zhagnsan");
	yure.put("02","lisi");

	jiuye.put("01","zhaoliu");
	jiuye.put("02","wangwu");



	//遍历czbk集合。获取所有的教室。
	Iterator<String> it = czbk.keySet().iterator();

	while(it.hasNext())
	{
		String roomName = it.next();
		HashMap<String,String> room = czbk.get(roomName);
		
		System.out.println(roomName);
		getStudentInfo(room);
	}

// getStudentInfo(jiuye);
// getStudentInfo(yure);
*/

}
public static void getStudentInfo(HashMap<String,String> roomMap)
{
	Iterator<String> it = roomMap.keySet().iterator();

	while(it.hasNext())
	{
		String id = it.next();
		String name = roomMap.get(id);
		System.out.println(id+":"+name);
	}
}

}