更新特定的HashMap键值

I am trying to update a specific HashMap key value, however, the value I am updating is being updated for all my key values. I have a HashMap of key type room (my own class) and a value of 2D int array which signifies the availability of a room.

我正在尝试更新特定的HashMap键值,但是,我正在为我的所有键值更新正在更新的值。我有一个关键类型房间的HashMap(我自己的类)和一个2D int数组的值,表示房间的可用性。

I have a Room object which is the room (key) I want to update. The function allocate room isn't important, it just allocates a room based on a certain criteria.

我有一个Room对象,这是我要更新的房间(键)。功能分配空间并不重要,它只是根据某个标准分配房间。

row and column are just the position in the 2D array which should be updated. However, all key values at this position are being updated instead of just one specific key value.

行和列只是2D数组中应该更新的位置。但是,此位置的所有键值都在更新,而不是仅更新一个特定键值。

Could anyone please shed some light on where I am going wrong? Thanks in advance!

有谁能请说明我出错的地方?提前致谢!

The way listOfRooms is generated:

生成listOfRooms的方式:

//Rooms are added to the list as such
listOfRooms.add(new Room ("001", 72, "Lecture", "YY"));

//This function is called which adds the room and an int 2D array to a hash map
public HashMap<Room,int[][]> finaliseRooms(){ 
    int[][] roomAvailability = new int[][]{ 
        {0,0,0,0,0,0,0,0,0}, 
        {0,0,0,0,0,0,0,0,0}, 
        {0,0,0,0,0,0,0,0,0}, 
        {0,0,0,0,0,0,0,0,0}, 
        {0,0,0,0,0,0,0,0,0} }; 
     for(Room room : listOfRooms){ 
        finalListOfRooms.put(room, roomAvailability); 
     } 
     return finalListOfRooms;
}

Changing the value of a specific key (at this point, listOfRooms has been equated to the returned value finalListOfRooms):

更改特定键的值(此时,listOfRooms已等同于返回值finalListOfRooms):

//This is where I try to change the value of a specific key
HashMap<Room, int[][]> a = new HashMap<Room, int[][]>(listOfRooms);
Room bestRoom = allocateRoom(a, randomMLSC, row, column);

String building = bestRoom.getRoomBuilding().toString();
String roomnum = bestRoom.getRoomNumber().toString();

for(Map.Entry<Room, int[][]> entry : a.entrySet()){
   if(entry.getKey().getRoomBuilding().toString().equals(building)){
       if(entry.getKey().getRoomNumber().toString().equals(roomnum)){
            int[][] val = entry.getValue();
            if(val[row][column]==0){
               val[row][column] = 1;
            }
        }   
    }
}

allocateRoom:

public Room allocateRoom(HashMap<Room, int[][]> listOfRooms, ModuleLecturerStudentCombination mlsc, int row, int column){
        ArrayList<Room> availableRooms = new ArrayList<Room>();

        for(Map.Entry<Room, int[][]> entry : listOfRooms.entrySet()){
            int[][] av = entry.getValue();
            if(av[row][column]==0){
                availableRooms.add(entry.getKey());
            }
            //goes on to do more stuff, not with listOfRooms
        }
}

1 个解决方案

#1

In the finaliseRooms method you assign the same array to every key, meaning that when one entry changes, all will be changed. You should move the declaration of roomAvailability inside the for each loop.

在finaliseRooms方法中,您为每个键分配相同的数组,这意味着当一个条目更改时,所有条目都将更改。您应该在for循环中移动roomAvailability的声明。