Map拓展：：集合的嵌套。 - 黑马程序员技术交流社区

import java.util.*;
class Demo
{
public static void main(String [] args)
{
duiX();
HashMap<String,HashMap<String,String>> CSDN=new HashMap<String,HashMap<String,String>> ();
HashMap<String,String> JC=new HashMap<String,String> ();
HashMap<String,String> JY=new HashMap<String,String> ();
CSDN.put("基础班",JC);
CSDN.put("就业班",JY);
JC.put("416","张三");
JC.put("445","李四");
JY.put("332","王五");
JY.put("329","马六");
//getInfo(JC); //获取某个教室学生信息。
for (Iterator<String> it=CSDN.keySet().iterator();it.hasNext(); )
{
String roomName=it.next();
HashMap<String,String> room=CSDN.get(roomName);
System.out.println(roomName+"::");
getInfo(room); //遍历获取所有班级的学生信息。room会传进所有的班级名。
}
}
public static void getInfo(HashMap<String,String> room)
{
for (Iterator<String> it=room.keySet().iterator();it.hasNext(); )
{
String id=it.next();
String name=room.get(id);
System.out.println(id+"++"+name);
}
}
public static void getInfo_2(List<Student> list)
{
for (Iterator<Student> it=list.iterator();it.hasNext(); )
{
Student s=it.next();
System.out.println(s);
}
}
public static void duiX()
{
HashMap<String,List<Student>> CSDN=new HashMap<String,List<Student>> ();
List<Student> JC=new ArrayList<Student> ();
List<Student> JY=new ArrayList<Student> ();
CSDN.put("基础班",JC);
CSDN.put("就业班",JY);
JC.add(new Student("01","zhangsan"));
JC.add(new Student("02","lixiaosi"));
JY.add(new Student("04","wangwu"));
JY.add(new Student("06","zhaoliu"));
for (Iterator<String> it=CSDN.keySet().iterator();it.hasNext(); )
{
String roomName=it.next();
List<Student> room=CSDN.get(roomName);
System.out.println(roomName);
getInfo_2(room);
}
}
}
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;
}
}

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