handling java collections object to filter data

Question

I have a hibernate query that returns a list of notifications. Notifications object has a Set

Notifications:

private BigDecimal id;
private BigDecimal createdBy;
private Date createDate;
private BigDecimal deletedBy;
private BigDecimal deletedDate;
private Set<Boards> notificationBoards = new HashSet<Boards>();

Boards:

private BigDecimal id;
private BigDecimal createdBy;
private Date createDate;

My query gives me a list of Notifications. I have to filter the Notifications based on board Id. So i need to iterate boards to check for id. If baords id=10 for example then i add to new list else ignore. So i thought i will form another new list of Notifications with only board id = 10. Below is my loop

 public List<Notifications> getNotificationList(List<Notifications> notification, Users loggedInUserObj){
    List<Notifications> notificationLi = new ArrayList<Notifications>(); 
    Set<Boards> boardLi = new HashSet<Boards>();
    Boards b = new Boards();
    Notifications n = new Notifications();
    if(notification != null && notification.size() > 0){
       for(Notifications notificationObj : notification){ 
           n = notificationObj;
           Set<Boards> notificationBoards = notificationObj.getNotificationBoards();
            for(Boards board: notificationBoards){
                 if(board.getId() == loggedInUserObj.getBoardObj().getId()){
                    b = board;  
                 }
                boardLi.add(b); 
            }               
           n.setNotificationBoards(boardLi);
       }
       notificationLi.add(n);
    }
    return notificationLi;        
}

I am getting only one Notifications instaed of a list(I am expecting 2 Notifications as per data) and boards are always null. Can someone point out whats wrong and a better way of doing the same?

Hi can you please post your sample data? – Suraj Gautam Jul 04 '20 at 06:46 — Suraj Gautam, Jul 04 '20 at 06:46

Eklavya · Accepted Answer · 2020-07-04T07:16:04.720

You need to do some fix

Use equals when comparing boardId of BigDecimal type
Add notification inside for loop when iterate list of notification
Add board in list inside if condition
Create object of Notification and Boards inside loop

 public List<Notifications> getNotificationList(List<Notifications> notification, Users loggedInUserObj){
    List<Notifications> notificationLi = new ArrayList<Notifications>(); 
    if(notification != null && notification.size() > 0){
       for(Notifications notificationObj : notification){ 
           Notifications n = new Notifications();
           n = notificationObj;
           Set<Boards> boardLi = new HashSet<Boards>();
           Set<Boards> notificationBoards = notificationObj.getNotificationBoards();
            for(Boards board: notificationBoards){
                 if(board.getId().equals(loggedInUserObj.getBoardObj().getId())){
                    boardLi.add(board);  
                 }
            }               
           n.setNotificationBoards(boardLi);
           notificationLi.add(n);
       }
    }
    return notificationLi;        
}

You can use Java stream API for filtering Boards

Set<Boards> boardLi = notificationObj.getNotificationBoards()
               .stream()
               .filter(board -> board.getId().equals(loggedInUserObj.getBoardObj().getId()))
               .collect(Collectors.toSet());

score 0 · Answer 2 · answered Jul 04 '20 at 06:47

0

You are comparing two BigDecimals using ==. Use equals.

board.getId().equals(loggedInUserObj.getBoardObj().getId())

Read: What is the difference between == and equals() in Java?

answered Jul 04 '20 at 06:47

Thiyagu

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handling java collections object to filter data

2 Answers2