当我尝试在Realm数据库Android中向RealmList添加新对象时出现问题。我总是得到NullPointer错误:
Global.USER_LOGGED.getProductsGrid()添加(pFinal);
这是我的模特:
@RealmClass
public class UserRealm extends RealmObject implements Serializable {
private String email;
private String password;
private String tokenId;
private String tokenSecret;
private String creationDate;
private RealmList<ProductRealm> productsGrid; //Temp table to load category products
private CartRealm cart; //One-to-one relationship
/*GETTERS & SETTERS*/
...
}
@RealmClass
public class ProductRealm extends RealmObject implements Serializable {
private String catId; //Only one category per product. In generic case many category per product
private String entityId;
private String parentId;
private String typeId;
private String sku;
private String canaryProduct;
private String premium;
private String brand;
private String dinitosQty;
private String name;
private String ean;
private String description;
private String shortDescription;
private String attributeSet;
private String weight;
private String isSaleable;
private String imageUrl;
private String unit;
private String unitFresh;
private String childrenSelected;
private float price;
private float minWeight;
private float quantityWeight;
private int quantity;
private int stock;
private int typeOfAttribute; //0: Per units | 1: Per weight
private RealmList<AttributeRealm> attributeItems;
private RealmList<ProductRealm> children;
/* GETTERS & SETTERS */
...
}
这是代码:
public static void parseProducts(String result){
Logs.MessageLogs("parseProducts", result, "v", Global.SHOW_LOGS);
Object product = null;
JSONObject json = null;
ProductRealm pFinal, p = new ProductRealm();
try {
json = new JSONObject(result);
if(Global.USER_LOGGED.getProductsGrid().size() > 0)
_CRUDDatabase.clearProductsGrid(Global.REALM);
for (Iterator<?> iterator = json.keys(); iterator.hasNext(); ) {
String key = (String) iterator.next();
if (json.get(key) instanceof JSONObject) { //Category with children
product = ((JSONObject) json.get(key));
Global.REALM.beginTransaction();
pFinal = Global.REALM.createObject(ProductRealm.class);
pFinal = _CRUDDatabase.createNewProduct(Global.PREVIOUS_CATEGORY.getId(), product);
Global.USER_LOGGED.getProductsGrid().add(pFinal);
Global.REALM.commitTransaction();
}
}
} catch (JSONException e) {
e.printStackTrace();
} catch (Exception ex){
ex.printStackTrace();
}
}
Global.USSER_LOGGED是一个Singleton,当前用户已登录:
public static UserRealm USER_LOGGED;
堆栈追踪:
06-23 15:16:32.619 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? java.lang.NullPointerException
06-23 15:16:32.619 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at io.realm.RealmList.add(RealmList.java:122)
06-23 15:16:32.619 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at com.singularfactory.ecommerceapp.utility.UtilityDB.parseProducts(UtilityDB.java:283)
06-23 15:16:32.619 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at com.singularfactory.ecommerceapp.fragment.ShopViewPagerFragment.OAuthResponse(ShopViewPagerFragment.java:148)
06-23 15:16:32.623 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at com.singularfactory.ecommerceapp.utility.WebService$getProductsByCategoryIdWithOAuth10a.onPostExecute(WebService.java:239)
06-23 15:16:32.623 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at com.singularfactory.ecommerceapp.utility.WebService$getProductsByCategoryIdWithOAuth10a.onPostExecute(WebService.java:187)
06-23 15:16:32.623 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at android.os.AsyncTask.finish(AsyncTask.java:632)
06-23 15:16:32.639 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at android.os.AsyncTask.access$600(AsyncTask.java:177)
06-23 15:16:32.639 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
06-23 15:16:32.639 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at android.os.Handler.dispatchMessage(Handler.java:102)
06-23 15:16:32.643 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at android.os.Looper.loop(Looper.java:136)
06-23 15:16:32.643 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at android.app.ActivityThread.main(ActivityThread.java:5001)
06-23 15:16:32.643 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at java.lang.reflect.Method.invokeNative(Native Method)
06-23 15:16:32.643 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at java.lang.reflect.Method.invoke(Method.java:515)
06-23 15:16:32.643 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
06-23 15:16:32.643 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
06-23 15:16:32.643 17555-17555/com.singularfactory.ecommerceapp.ecommerceappW/System.err? at dalvik.system.NativeStart.main(Native Method)
我正在阅读Realm doc,我发现创建RealmList有两种模式:托管和非托管。我正在尝试创建两者,但我总是有同样的错误。
如何在数据库中创建对象并分配给RealmList? 我的代码有什么问题?
提前致谢:)
更新
我的单身人士课程:
public class Global {
private static Global instance = null;
...
//Realm
public static Realm REALM; //Database Realm
public static String DATABASE_NAME; //Name of Realm database
public static UserRealm USER_LOGGED; //Object of the user logged
...
private Global() {
//Realm
REALM = null;
DATABASE_NAME = "keymarket.realm";
USER_LOGGED = null;
...
}
public static Global getInstance(){
if(instance == null){
instance = new Global();
}
return instance;
}
答案 0 :(得分:2)
在将对象添加到列表之前,需要将对象添加到域中,因为内部Realm将调用getId(或任何获取它的主键的方法)以将对象添加到列表中。由于它使用代理方法并且未将对象添加到领域,因此将获得空指针异常..