자바 에서 집합 하 는 내장: 내장 집합, 내장 keySet 옮 겨 다 니 기, 내장 entry Set 옮 겨 다 니 기

public static void main(String[] args)
{
    /**
     *           ，                
     *         Map   ，          Map   
     *                 
     */
    Map boys = new HashMap<>();
    Map girls = new HashMap<>();
    boys.put(1,"  ");
    boys.put(2,"  ");
    boys.put(3,"  ");
    girls.put(1,"  ");
    girls.put(2,"  ");
    girls.put(3,"  ");
    Map> Student = new HashMap<>();
    Student.put(1,boys);
    Student.put(2,girls);
    System.out.println(Student);

    //  Student    keySet     Set  
    Set S1 = Student.keySet();
    //  Set  
    Iterator Stu_it = S1.iterator();
    while (Stu_it.hasNext()) {
        //it.next      Set    ,Student    
        Integer Stu_key = Stu_it.next();
        //Student     get   ,    Map  
        Map Stu_value = Student.get(Stu_key);
        Set S2 = Stu_value.keySet();
        Iterator it = S2.iterator();
        while (it.hasNext()) {
            Integer key = it.next();
            String value = Stu_value.get(key);
            System.out.println(key + "=" + value);
        }
    }
    System.out.println("==================================");
    
    //    for    
    for(Integer Stu__key : Student.keySet())
    {
        Map Stu__value = Student.get(Stu__key);
        for (Integer key : Stu__value.keySet())
        {
            String value = Stu__value.get(key);
            System.out.println(key + "=" +value);
        }
    }
}

public static void main(String[] args)
{
    /**
     *           ，                
     *         Map   ，          Map   
     *                 
     */
    Map boys = new HashMap<>();
    Map girls = new HashMap<>();
    boys.put(1,"  ");
    boys.put(2,"  ");
    boys.put(3,"  ");
    girls.put(1,"  ");
    girls.put(2,"  ");
    girls.put(3,"  ");
    Map> Student = new HashMap<>();
    Student.put(1,boys);
    Student.put(2,girls);
    System.out.println(Student);

    //  Student    entrySet  , Student          ,   Set  
    Set>> Stu = Student.entrySet();
    //     Set  
    Iterator>> Stu_it = Stu.iterator();
    while (Stu_it.hasNext())
    {
        //Stu_it.next  ,    Student          
        Map.Entry> Stu_entry = Stu_it.next();
        Integer Stu_key = Stu_entry.getKey();
        Map Stu_value = Stu_entry.getValue();
        System.out.println(Stu_key + "=" + Stu_value);
        //  Person  entrySet  ,         Set  
        Set> S = Stu_value.entrySet();
        //  Set  
        Iterator> it = S.iterator();
        while (it.hasNext())
        {
            //  boys girls           
            Map.Entry entry = it.next();
            Integer key = entry.getKey();
            String value = entry.getValue();
            System.out.println(key + "="+ value);
        }
    }
    //    for    
    for(Map.Entry> Stud : Student.entrySet())
    {
        Integer Stu__key = Stud.getKey();
        Map Stu__value = Stud.getValue();
        System.out.println(Stu__key + "=" + Stu__value);
        for(Map.Entry M : Stu__value.entrySet())
        {
            Integer key_ = M.getKey();
            String value_ = M.getValue();
            System.out.println(key_ + "=" + value_);
        }
    }
}