{"id":18143,"date":"2022-10-29T14:31:13","date_gmt":"2022-10-29T09:01:13","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-how-to-implement-and-fire-an-event-when-a-change-occurs-in-a-property-of-t-in-list-within-the-owning-class-in-java\/"},"modified":"2022-10-29T14:31:13","modified_gmt":"2022-10-29T09:01:13","slug":"solved-how-to-implement-and-fire-an-event-when-a-change-occurs-in-a-property-of-t-in-list-within-the-owning-class-in-java","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-how-to-implement-and-fire-an-event-when-a-change-occurs-in-a-property-of-t-in-list-within-the-owning-class-in-java\/","title":{"rendered":"[Solved] How to implement and fire an event when a change occurs in a property of `T` in `List` within the owning class in Java"},"content":{"rendered":"

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I just ported ItemPropertyChangedNotifyingList to ItemChangeList.<\/p>\n

In code, I changed this part.<\/p>\n

    \n
  1. Used ‘ArrayList’ to hold elements instead of ‘List` in C#<\/li>\n
  2. In copyTo<\/code>, I used Java 8 Stream. Since you tag ‘android’, I used Lightweight-Stream-API<\/a> to achieve same feature of copyTo.<\/li>\n
  3. Java doesn’t support get<\/code>, set<\/code> syntax, i divide to two methods.<\/li>\n<\/ol>\n
    import com.annimon.stream.Stream;\n\nimport java.util.ArrayList;\nimport java.util.Iterator;\nimport java.util.List;\n\npublic class ItemChangedList<T> {\n    private List<T> _listImplementation = new ArrayList<>();\n    private List<OnPropertyChangedObserver<T>> _changedObserverList = new ArrayList<>();\n\n    public static final String ITEM_ADDED = \"bbed36af-0b7b-4e53-abc9-02d6a14d7f34\";\n    public static final String ITEM_REMOVED = \"7390116e-586d-4e62-9343-5b82b0a8c6c5\";\n\n    public void add(T item) {\n        sendPropertyChanged(item, ITEM_ADDED);\n        _listImplementation.add(item);\n    }\n\n    public Iterator<T> iterator() {\n        return _listImplementation.iterator();\n    }\n\n    public void clear() {\n        for (T item : _listImplementation) {\n            sendPropertyChanged(item, ITEM_REMOVED);\n        }\n        _listImplementation.clear();\n    }\n\n    public boolean contains(T item) {\n        return _listImplementation.contains(item);\n    }\n\n    public void copyTo(T[] array, int arrayIndex) {\n        \/\/ Using https:\/\/github.com\/aNNiMON\/Lightweight-Stream-API\n        _listImplementation.addAll(Stream.of(array).skip(arrayIndex).toList());\n\n        \/\/ Traditional Java way\n        \/\/ _listImplementation.addAll(Arrays.stream(array).skip(arrayIndex).collect(Collectors.toList()));\n    }\n\n    public boolean remove(T item) {\n        sendPropertyChanged(item, ITEM_REMOVED);\n        return _listImplementation.remove(item);\n    }\n\n    public int count() {\n        return _listImplementation.size();\n    }\n\n    public boolean isReadOnly() {\n        return false;\n    }\n\n    public int indexOf(T item) {\n        return _listImplementation.indexOf(item);\n    }\n\n    public void insert(int index, T item) {\n        sendPropertyChanged(item, ITEM_ADDED);\n        _listImplementation.add(index, item);\n    }\n\n    public void removeAt(int index) {\n        _listImplementation.remove(index);\n    }\n\n    public T get(int index) {\n        return _listImplementation.get(index);\n    }\n\n    public void set(int index, T item) {\n        _listImplementation.set(index, item);\n    }\n\n    public void addObserver(OnPropertyChangedObserver<T> observer) {\n        _changedObserverList.add(observer);\n    }\n\n    public void removeObserver(OnPropertyChangedObserver<T> observer) {\n        _changedObserverList.remove(observer);\n    }\n\n    public void clearObserver() {\n        _changedObserverList.clear();\n    }\n\n    private void sendPropertyChanged(T item, String args) {\n        for (OnPropertyChangedObserver<T> observer : _changedObserverList) {\n            observer.onChanged(item, args);\n        }\n    }\n\n    public interface OnPropertyChangedObserver<T> {\n        void onChanged(T item, String args);\n    }\n}\n\n<\/code><\/pre>\n
    Other way is extends ArrayList instead _listImplementation<\/code>. it can be provide more functionally. Personally, I prefer this way. Gist<\/a><\/p>\n
    Edit-1) Oh, i forget add args in OnPropertyChangeObserver. <\/p>\n
    Edit-2) Let Kotlin optimize this! Gist<\/a><\/p>\n<\/p><\/div>\n
    <\/div>\n<\/div>\n
                <\/span> <\/p><\/div>\n<\/div>\n
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    solved How to implement and fire an event when a change occurs in a property of `T` in `List` within the owning class in Java <\/p>\n","protected":false},"excerpt":{"rendered":"
    [ad_1] I just ported ItemPropertyChangedNotifyingList to ItemChangeList. In code, I changed this part. Used ‘ArrayList’ to hold elements instead of ‘List` in C# In copyTo, I used Java 8 Stream. Since you tag ‘android’, I used Lightweight-Stream-API to achieve same feature of copyTo. Java doesn’t support get, set syntax, i divide to two methods. import … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[452,323],"class_list":["post-18143","post","type-post","status-publish","format-standard","hentry","category-solved","tag-android","tag-java"],"yoast_head":"\n[Solved] How to implement and fire an event when a change occurs in a property of `T` in `List` within the owning class in Java - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-how-to-implement-and-fire-an-event-when-a-change-occurs-in-a-property-of-t-in-list-within-the-owning-class-in-java\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] How to implement and fire an event when a change occurs in a property of `T` in `List` within the owning class in Java - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] I just ported ItemPropertyChangedNotifyingList to ItemChangeList. 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