Android changing order of items run-time in Realm Recyclerview - realm

Question

I need to order the list of items based on a field say starredAt
I am loading the data in the recyclerview from Realm DB using RealmRecyclerView by thorbenprimke
The field changes it value on user's action i.e when user presses star button the item should be moved to top.
For this I am just updating the starredAt field of the object.
The items are already sorted by starredAt so realm loads the updated list but it randomly adds one more item to the recyclerview.
CheatSheet.java
public class CheatSheet extends RealmObject {
#PrimaryKey
private String id;
private RealmList<Item> items;
private String title;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public RealmList<Item> getItems() {
return items;
}
public void setItems(RealmList<Item> items) {
this.items = items;
}
}
Item.java
public class Item extends RealmObject {
#PrimaryKey
private String id;
private String description;
private Date starredAt;
public Item() {
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Date getStarredAt() {
return starredAt;
}
public void setStarredAt(Date starredAt) {
this.starredAt = starredAt;
}
}
CheatSheetActivity.java
public class MainActivity extends AppCompatActivity {
RealmRecyclerView revItems;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setData();
}
private void setData() {
rvItems = (RealmRecyclerView) findViewById(R.id.rev_items);
RealmResults<Item> items = Realm.getDefaultInstance().where(CheatSheet.class)
.equalTo("id", "some-id").findFirst().getItems()
.where()
.findAllSorted("starredAt", Sort.DESCENDING);
ItemRealmListAdapter itemRealmListAdapter =
new ItemRealmListAdapter(this, items,
true, true);
rvItems.setAdapter(itemRealmListAdapter);
}
ItemRealmListAdapter.java
public class ItemRealmListAdapter extends RealmBasedRecyclerViewAdapter<Item,
ItemRealmListAdapter.ItemViewHolder> {
RealmResults<Item> mItems;
public ItemRealmListAdapter(Context context, RealmResults<Item> realmResults,
boolean automaticUpdate, boolean animateResults) {
super(context, realmResults, automaticUpdate, animateResults);
this.mItems = realmResults;
}
#Override
public ItemViewHolder onCreateRealmViewHolder(ViewGroup viewGroup, int i) {
return new ItemViewHolder(LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.item_layout_cs_text, viewGroup, false));
}
public Item getItem(int position) {
return mItems.get(position);
}
#Override
public void onBindRealmViewHolder(ItemViewHolder itemViewHolder, int position) {
itemViewHolder.txtBody.setText(getItem(position).getDescription());
if (getItem(position).getStarredAt() != null) {
itemViewHolder.imvStar.setImageResource(R.drawable.ic_star_yellow);
}
itemViewHolder.imvStar.setOnClickListener(v -> handleStarClick(v,position));
}
private void handleStarClick(View v, int position) {
if (getItem(position).getStarredAt() != null) {
((ImageView) v).setImageResource(R.drawable.ic_star);
CheatSheetStorage.unStarItem("some-id", getItem(position));
} else {
((ImageView) v).setImageResource(R.drawable.ic_star_yellow);
CheatSheetStorage.starItem("some-id", getItem(position));
}
}
public static class ItemViewHolder extends RealmViewHolder {
#Bind(R.id.txt_cheat_sheet)
TextView txtBody;
#Bind(R.id.img_star)
ImageView imvStar;
public ItemViewHolder(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
}
}
}
CheatSheetStorage.java
public class CheatSheetStorage {
public static void unStarItem(String cheatSheetId, Item item) {
Realm realm = Realm.getDefaultInstance();
realm.beginTransaction();
CheatSheet cheatSheet = getCheatSheetById(cheatSheetId);
Item itemDB = cheatSheet.getItems().where().equalTo("id", item.getId()).findFirst();
itemDB.setStarredAt(null);
realm.commitTransaction();
}
public static void starItem(String cheatSheetId, Item item) {
Realm realm = Realm.getDefaultInstance();
realm.beginTransaction();
CheatSheet cheatSheet = getCheatSheetById(cheatSheetId);
Item itemDB = cheatSheet.getItems().where().equalTo("id", item.getId()).findFirst();
itemDB.setStarredAt(new Date());
realm.commitTransaction();
}
}
Please refer following screenshots for clearer idea :
Screenshot before starring
Screenshot after starring the sixth item

Answer 1

#Rohan-Peshkar - You will have to provide a animateExtraColumnName value to the adapter. For the animations, the adapter keeps track of the items and since that item's id doesn't change, the list isn't updated. With an additional column (in your case that should be the starredAt column - as long as it is stored as an Integer), the diffing algorithm will detect a change and the order is updated.
For reference: https://github.com/thorbenprimke/realm-recyclerview/blob/2835a543dce20993d8f98a4f773fa0e67132ce52/library/src/main/java/io/realm/RealmBasedRecyclerViewAdapter.java#L177
You can also check out the MainActivity in the example folder. The example changes a row's text from "ABC" to "Updated ABC" and the list recognizes the change because both the primary key and the quote field are used to basically create a composite key for diffing purposes.