Keynote for 30 min presentation about "Why you should try Realm" at GDG-Korea

1. Realm
The Finest Artist

2. Realm [Relm]

3. 렘 [레엠]

4. Realm = Kingdom

5. Realm = Mobile Database

6. Realm
Replacement for SQLite & Core Data
Android, Android Wear, iOS, OS X, Watch OS
Java, Kotlin, Objective-C, Swift

7. Why Realm?

8. Realm
Very Fast
ORM like models & queries
RealmResults auto refresh
More features…
Open source
Documentation in Korean

9. How Fast?

13. Gson vs Realm
This test is to compare the speed of Gson and Realm with an extremely simple object model. The overall result of the test shows that Realm
performs a little faster than Gson. However, it could show different results in other test conditions. Refer to the appendix for further information.
Gson.toJson
Gson.fromJson
Realm.createObject
copyToRealm
Milisecond
0 300 600 900 1200

14. ORM like models & queries

15. Model
public class User extends RealmObject {
@PrimaryKey
private String name;
private int age;
@Ignore
private int sessionId;
// + Standard getters & setters generated by your IDE
}

16. Relation
public class Email extends RealmObject {
private String address;
private boolean active;
}
// Many to One
public class Contact extends RealmObject {
private Email email;
}
// Many to Many
public class Contact extends RealmObject {
private RealmList<Email> emails;
}

17. Write
realm.beginTransaction();
User user = realm.createObject(User.class); // Create a new object
user.setName("John");
user.setEmail("john@corporation.com");
realm.commitTransaction();

18. Write
User user = new User("John");
user.setEmail("john@corporation.com");
realm.beginTransaction();
realm.copyToRealm(user); // Copy the object to Realm.
realm.copyToRealmOrUpdate(user);
realm.commitTransaction();

19. Query
// Fluent interface
RealmResults<User> result = realm.where(User.class)
.sort("age");
.beginGroup()
.equalTo("name", "John")
.or()
.equalTo("name", "Peter")
.endGroup()
.findAll();
for (User user : result) {
// do something...
}

20. Query Options
// Conditions
between(), greaterThan(), lessThan(), greaterThanOrEqualTo() & lessThanOrEqualTo()
equalTo() & notEqualTo()
contains(), beginsWith() & endsWith()
isNull() & isNotNull()
beginsWith() & endsWith() & contains()
// Conditions Grouping
beginGroup() & endGroup() & not() & or()
// Sorting
RealmResults<User> result = realm.where(User.class).findAll();
result.sort("age", RealmResults.SORT_ORDER_DESCENDING);
// Querying
findAll() & findFirst() & findAllSorted()

21. RealmResults Auto-refresh

22. RealmResults
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
RealmResults<Post> realmResults;
public RecyclerViewAdapter(Realm realm) {
realmResults = realm.where(Post.class).findAll();
}
@Override
public int getItemCount() { return realmResults.size(); }
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(layoutRes, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Post post = realmResults.get(position);
// do something...
}
}

23. RealmResults
public class UserRecyclerAdapter extends RecyclerView.Adapter<ChatRecyclerAdapter.ViewHolder> {
List<User> users;
public ChatRecyclerAdapter() { /*...*/ }
public void setUsers(List<User> users) { this.users = users; }
@Override
public int getItemCount() { return users == null ? 0 : users.size(); }
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(layoutRes, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
User user = users.get(position);
/*...*/
}
}

24. More Features

25. More Features
Encryption (AES-256)
Multiple Databases
In-Memory Realm
Listeners
Migration
Realm Browser (Mac OS)

26. Realm Configuration
RealmConfiguration config1 = new RealmConfiguration.Builder(context)
.name("myrealm1.realm")
.encryptionKey(getKey1())
.schemaVersion(1)
.setModules(new MySchemaModule1())
.migration(new MyMigration1())
.build();
RealmConfiguration config2 = new RealmConfiguration.Builder(context)
.name("myrealm2.realm")
.encryptionKey(null)
.inMemory()
.schemaVersion(2)
.setModules(new MySchemaModule2())
.migration(new MyMigration2())
.build();

27. Realm Listener
private RealmChangeListener realmListener;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
realmListener = new RealmChangeListener() {
@Override
public void onChange() {
// ... do something with the updates (UI, etc.) ...
}
};
realm.addChangeListener(realmListener);
}
@Override
public void onDestroy() {
super.onDestroy();
realm.removeChangeListener(realmListener);
}

28. Realm Migration
public class Migration implements RealmMigration {
@Override
public long execute(Realm realm, long version) {
// Migrate from version 0 to version 1
if (version == 0) {
Table personTable = realm.getTable(Person.class);
long fistNameIndex = getIndexForProperty(personTable, "firstName");
long lastNameIndex = getIndexForProperty(personTable, "lastName");
long fullNameIndex = personTable.addColumn(ColumnType.STRING, "fullName");
personTable.removeColumn(getIndexForProperty(personTable, "firstName"));
personTable.removeColumn(getIndexForProperty(personTable, "lastName"));
version++;
}
return version;
}
}
https://github.com/realm/realm-java/blob/master/examples/migrationExample

29. Realm Browser

30. Open Source

31. Documentation in Korean

32. Current Limitations
RealmObject
Only private field
Only default getter & setter
Static field & method are allowed
Null Values
Threads

33. Users

34. More
Homepage: http://realm.io/
Facebook: http://fb.com/groups/realmkr
Email: kr@realm.io

35. Use Case
InstagRealm
https://github.com/TheFinestArtist/InstagRealm

36. InstagRealm

37. Features
Instagram Tag API
ScrollView, ListView, RecyclerView, CardView
Infinite Scroll (Paging), Swipe to Refresh
Retrofit
Gson
EventBus
Royal
Fresco, Butterknife, RecyclerView-Animator, Logger

38. Flow
Retrofit (Instagram Tag API)
=> Gson (Serialize)
=> Realm (Insert data)
=> EventBus
=> Update UI & Notify Adpater

39. RestAdapter
private static Gson gson = new GsonBuilder()
.setExclusionStrategies(new ExclusionStrategy() {
@Override
public boolean shouldSkipField(FieldAttributes f) {
return f.getDeclaringClass().equals(RealmObject.class);
}
@Override
public boolean shouldSkipClass(Class<?> clazz) {
return false;
}
})
.create();
private static RestAdapter restAdapter = new RestAdapter.Builder()
.setEndpoint(END_POINT)
.setConverter(new GsonConverter(gson))
.setRequestInterceptor(requestInterceptor)
.build();
private static InstagramService instagramService = restAdapter.create(InstagramService.class);

40. Instagram API
public static void getTag(final Activity activity, final Class<? extends RoyalDatabase> clazz, String next) {
instagramService.getTags("art", accessToken, next, new Callback<TagsCallback>() {
@Override
public void success(TagsCallback tagsCallback, Response response) {
RoyalTransaction.save(clazz, tagsCallback.data);
if (ScrollViewDatabase.class.equals(clazz))
EventBus.getDefault().post(new OnScrollViewUpdateEvent(tagsCallback.pagination.next_max_tag_id, tagsCallback.data));
if (ListViewDatabase.class.equals(clazz))
EventBus.getDefault().post(new OnListViewUpdateEvent(tagsCallback.pagination.next_max_tag_id));
if (RecyclerViewDatabase.class.equals(clazz))
EventBus.getDefault().post(new OnRecyclerViewUpdateEvent(tagsCallback.pagination.next_max_tag_id));
if (CardViewDatabase.class.equals(clazz))
EventBus.getDefault().post(new OnCardViewUpdateEvent(tagsCallback.pagination.next_max_tag_id));
}
@Override
public void failure(RetrofitError error) {
SnackBar.alert(activity, "Please check your network status!");
}
});
}

41. OnEvent
int itemCount = 0;
public void onEvent(OnRecyclerViewUpdateEvent event) {
swipeRefreshLayout.setRefreshing(false);
if (event.isFailed())
return;
next = event.getNext();
if (itemCount < adapter.getItemCount())
adapter.notifyItemRangeInserted(itemCount, adapter.getItemCount() - itemCount);
else
adapter.notifyItemRangeRemoved(itemCount, itemCount - adapter.getItemCount());
itemCount = adapter.getItemCount();
}

42. RecyclerViewAdapter
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
RealmResults<Post> realmResults;
public RecyclerViewAdapter(Realm realm) {
realmResults = realm.where(Post.class).findAll();
}
@Override
public int getItemCount() { return realmResults.size(); }
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(layoutRes, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Post post = realmResults.get(position);
// do something...
}
}

43. ListViewAdapter
public class ListViewAdapter extends RealmBaseAdapter<Post> implements ListAdapter {
public ListViewAdapter(Context context, RealmResults<Post> realmResults) {
super(context, realmResults, true);
}
static class ViewHolder {
ViewHolder(View view) { /*...*/ }
public void setPost(Post post) { /*...*/ }
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
/* ViewHolder Inflating */
Post post = realmResults.get(position);
viewHolder.setPost(post);
return convertView;
}
}

44. Use Case
InstagRealm
https://github.com/TheFinestArtist/InstagRealm

47. Thank You :)

48. Appendix
Test Device: Galaxy S3
Test Model
public class Contact {
public String address;
public String number;
public boolean active;
}
10000 times iteration per each test.
5 times test per each method
Test Code: https://github.com/Test-Codes/Realm-Java-Benchmark