如何在领域 android 数据库中存储 java 列表

Question

我们如何在领域 android 数据库中存储 java 列表。我尝试使用模型中存在的 setter 方法来存储它，但它不起作用，我在异常消息中得到 "Each element of 'value' must be a valid managed object"。

public void storeNewsList(String categoryId, List<News> newsList) { 
    Realm realm = Realm.getDefaultInstance(); 
    realm.beginTransaction(); 
    NewsList newsListObj = realm.createObject(NewsList.class); 
    newsListObj.setNewsList(new RealmList<>(newsList.toArray(new News[newsList.size()]))); 
    newsListObj.setCategoryId(categoryId); 
    realm.commitTransaction(); 
    realm.close(); 
} 

Answer 1

将代码替换为

public void storeNewsList(String categoryId, List<News> newsList) { 
    try(Realm realm = Realm.getDefaultInstance()) { 
        realm.executeTransaction(new Realm.Transaction() {
             @Override
             public void execute(Realm realm) {
                 NewsList newsListObj = new NewsList(); // <-- create unmanaged
                 RealmList<News> _newsList = new RealmList<>();
                 _newsList.addAll(newsList);
                 newsListObj.setNewsList(_newsList); 
                 newsListObj.setCategoryId(categoryId);
                 realm.insert(newsListObj); // <-- insert unmanaged to Realm
             }
        }); 
    }
} 

Answer 2

如果您使用的是@PrimaryKey，那么 insertOrUpdate 就可以了

try(Realm realm = Realm.getDefaultInstance()) {
                        realm.executeTransaction(new Realm.Transaction() {
                            @Override
                            public void execute(Realm realm) {
                                 RealmList<News> _newsList = new RealmList<>();
                                _newsList.addAll(myCustomArrayList);
                                realm.insertOrUpdate(_newsList); // <-- insert unmanaged to Realm

                            }
                        });
                    }