【汎用+集合フレームワーク】2つの簡単なルーチン

1汎型のネスト汎型の中はやはり汎型です
 

package package1;



import java.util.HashMap;

import java.util.Iterator;



public class MapDemo {

    public static void main(String[] args) {

        HashMap<String , HashMap<String , String>> school =

                new HashMap<String , HashMap<String , String>> ();

        

        HashMap<String , String> room1 = new HashMap<String , String>();

        HashMap<String , String> room2 = new HashMap<String , String>();

        

        school.put("room1",room1);

        school.put("room2",room2);

        room1.put("01", "yang");

        room1.put("02", "wang");

        room2.put("01", "sun");

        room2.put("02", "li");

        

        Iterator<String> it1 = school.keySet().iterator();

        while(it1.hasNext()){

            String room = it1.next();

            HashMap<String , String> roomm = school.get(room);

            System.out.println(room + ":" + roomm);

            getPersonInfo(roomm);

            

        }

        

        

        

    }



    private static void getPersonInfo(HashMap<String, String> room) {

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

        while(it.hasNext()){

            String id = it.next();

            String name = room.get(id);

            System.out.println(id + ":" + name);

        }

    }

}

 
実行結果:
room2:{01=sun, 02=li}01:sun02:liroom1:{01=yang, 02=wang}01:yang02:wang
 
 
 
 
 
 
2汎用型はパッケージ化されたクラスです

package package6;

import java.util.*;



class Student2{

    private String id;

    private String name;

    Student2(String id,String name){

        this.id=id;

        this.name=name;

    }

    public String toString(){

        return id+"   ~~   "+name;

    }

}



public class Test15 {

    public static void main(String[] args){

        HashMap<String,List<Student2>>qq=new HashMap<String,List<Student2>>();

        

        List <Student2>room1=new ArrayList<Student2>();

        List <Student2>room2=new ArrayList<Student2>();

        qq.put("first", room1);

        qq.put("second", room2);

        

        room1.add(new Student2("01", "zhang"));

        room1.add(new Student2("02", "wang"));

        room2.add(new Student2("01", "yang"));

        room2.add(new Student2("02", "chen"));

        

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

        while(it.hasNext()){

            String roomName=it.next();

            List<Student2> roomInfo=qq.get(roomName);

            System.out.println(roomName);

            getStudentInfo(roomInfo);

        }

    }

    

    

    public static void getStudentInfo(List<Student2> list){

        Iterator<Student2> it=list.iterator();

        while(it.hasNext()){

         Student2 s=it.next();

            System.out.println(s);

        }

    }

}

 
実行結果:
second01 ~~ yang02 ~~ chenfirst01 ~~ zhang02 ~~ wang