Getting NullPointer adding object to RealmList

Question

I have a problem when I try to add a new object to RealmList in Realm database Android. Always I'm getting NullPointer error at:

Global.USER_LOGGED.getProductsGrid().add(pFinal);

This is my models:

    @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 */
    ... 
}

This is the code:

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 is a Singleton with the currently user logged:

public static UserRealm USER_LOGGED;

Stack trace:

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)

I'm reading Realm doc's and I see that there are two modes to create RealmList: managed and non-managed. I'm trying to create both but I have always same error.

How can I create an object and assign to RealmList in database? What's wrong in my code?

Thanks in advance :)

UPDATE:

My Singleton class:

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;
    }

It seems you're accessing the object from a thread. Notice this from the documentation: "Moreover, asynchronous queries are currently not supported." — Pedro Oliveira, Jun 23 '15 at 14:24
I get the products from the server and when I get the response, I parse json obtained in this method, but this is not in a asynchronous call — Adae Rodríguez, Jun 23 '15 at 14:32
possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — Selvin, Jun 23 '15 at 14:36
I suggest you change the type of USER_LOGGED from UserRealm to String. Save the Id of the user there and every time you need to used it just perform a simple query. — Pedro Oliveira, Jun 23 '15 at 14:39
@PedroOliveira it doesn't matter it will be null as it is now ... he asumed that he set it but do not know android's application lifecycle — Selvin, Jun 23 '15 at 14:40
I think that is not the same case. The problem is the RealmList when I try to add new object. I'm sure that all is initialized and all have values but NullPointer is raised when execute .add() — Adae Rodríguez, Jun 23 '15 at 14:40
IT WILL NOT HELP ... you should build real singleton ... which will not return null (and fully created UserRealm object) — Selvin, Jun 23 '15 at 14:41
Why are you're saying it is null @Selvin? You don't see it's initialization. It could be a static value which is irrelevant to the "android's application lifecycle". — Pedro Oliveira, Jun 23 '15 at 14:45
yes it is ... fx: he set it in LoginActivity ... and start MainActivity ... app move to background ... gets killed ... he returns to MainActivity ... bang — Selvin, Jun 23 '15 at 14:46
Where do you see "onResume" or "onActivityCreated" on that stacktrace? An advice to you, don't play on the lottery @Selvin :P — Pedro Oliveira, Jun 23 '15 at 14:49
@AdaeRodríguez you need to call getInstance after Global. Also the fields from the singleton shouldn't be static — Pedro Oliveira, Jun 23 '15 at 14:51
I'm sure that Global.USER_LOGGED has value, and I made your change and I get the same error :( Anyway, I have Global.getInstance(); at onCreate in MainActivity — Adae Rodríguez, Jun 23 '15 at 14:53
Try adding pFinal to the Realm (copyToRealm) before adding it to the list — Pedro Oliveira, Jun 23 '15 at 14:55
It's very strange. I have used Realm in another projects with cart and list and NEVER I had this problem — Adae Rodríguez, Jun 23 '15 at 14:58
@PedroOliveira I made your change (Global.REALM.copyToRealm(pFinal)) and wonderfully it's worked. Could you explain me why I need copy the value before add to the list? I don't understand — Adae Rodríguez, Jun 23 '15 at 15:04
Another question that I have is: When I search an object that I deleted previously, Realm always find this deleted object. Have I copyToRealm also? — Adae Rodríguez, Jun 23 '15 at 15:08
You need to call removeFromRealm to remove it from the realm — Pedro Oliveira, Jun 23 '15 at 15:09

score 2 · Accepted Answer · answered Jun 23 '15 at 15:06

2

You need to add the object to the realm before adding it to a list because internally Realm will call getId (or whatever method to get it's primary key) in order to add the object to the list. Since it uses proxy methods and the object was not added to the realm you will get a null pointer exception..

answered Jun 23 '15 at 15:06

Pedro Oliveira

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I can't vote up, but It's worked!!. You are a crack!! – Adae Rodríguez Jun 23 '15 at 15:10
You can't upvote but you can mark as answer as far as I know :) It will help as much as a vote up. – Pedro Oliveira Jun 23 '15 at 15:11

Getting NullPointer adding object to RealmList

1 Answers1